[Improve](Config) add variant_max_json_key_length to limit variant json key length

[eldenmoon]

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[Thearas]

Thank you for your contribution to Apache Doris.
Don't know what should be done next? See How to process your PR.

Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[eldenmoon]

run buildall

[eldenmoon]

run buildall

[doris-robot]

TPC-H: Total hot run time: 30790 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpch-tools
Tpch sf100 test result on commit 1c9675b2e81e98dcf9c889110fa326d6119c5a88, data reload: false

------ Round 1 ----------------------------------
q1	17705	4807	4565	4565
q2	2068	320	199	199
q3	10199	1350	732	732
q4	10220	875	314	314
q5	7532	2097	1854	1854
q6	188	170	139	139
q7	869	734	591	591
q8	9276	1386	1055	1055
q9	4950	4635	4643	4635
q10	6818	1674	1277	1277
q11	541	300	296	296
q12	393	375	218	218
q13	17802	3817	3071	3071
q14	228	249	211	211
q15	643	524	514	514
q16	658	637	586	586
q17	660	788	521	521
q18	6705	6563	6274	6274
q19	1096	986	619	619
q20	390	338	238	238
q21	2657	1933	1957	1933
q22	1049	999	948	948
Total cold run time: 102647 ms
Total hot run time: 30790 ms

----- Round 2, with runtime_filter_mode=off -----
q1	4792	4733	4708	4708
q2	315	414	334	334
q3	2137	2695	2289	2289
q4	1313	1746	1347	1347
q5	4080	4017	4217	4017
q6	193	165	128	128
q7	1918	1862	1917	1862
q8	2661	2499	2465	2465
q9	7276	7286	7302	7286
q10	2493	2825	2246	2246
q11	561	480	468	468
q12	702	817	596	596
q13	3615	4099	3395	3395
q14	322	320	296	296
q15	563	533	514	514
q16	656	663	631	631
q17	1141	1274	1334	1274
q18	8156	8043	7696	7696
q19	895	857	888	857
q20	2040	2057	1934	1934
q21	4683	4617	4296	4296
q22	1061	1034	940	940
Total cold run time: 51573 ms
Total hot run time: 49579 ms

[doris-robot]

TPC-DS: Total hot run time: 173511 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpcds-tools
TPC-DS sf100 test result on commit 1c9675b2e81e98dcf9c889110fa326d6119c5a88, data reload: false

query5	4406	634	508	508
query6	346	233	216	216
query7	4223	444	265	265
query8	354	263	250	250
query9	8722	2866	2882	2866
query10	429	328	286	286
query11	15189	15062	14902	14902
query12	177	121	120	120
query13	1264	453	375	375
query14	5652	3090	2881	2881
query14_1	2651	2670	2708	2670
query15	208	192	173	173
query16	1013	490	420	420
query17	896	669	581	581
query18	2429	435	331	331
query19	208	178	154	154
query20	118	121	116	116
query21	220	137	118	118
query22	4171	3901	3888	3888
query23	16082	15606	15407	15407
query23_1	15251	15596	15386	15386
query24	7199	1569	1144	1144
query24_1	1171	1156	1180	1156
query25	549	458	409	409
query26	1246	270	155	155
query27	2758	448	281	281
query28	4583	2169	2147	2147
query29	788	549	449	449
query30	305	246	208	208
query31	788	629	566	566
query32	84	77	79	77
query33	527	381	316	316
query34	929	866	540	540
query35	715	777	665	665
query36	905	881	855	855
query37	183	93	88	88
query38	2673	2745	2651	2651
query39	776	766	741	741
query39_1	724	704	728	704
query40	216	130	117	117
query41	66	63	63	63
query42	97	97	95	95
query43	470	434	408	408
query44	1331	747	750	747
query45	188	185	172	172
query46	826	941	576	576
query47	1318	1492	1381	1381
query48	331	325	255	255
query49	619	432	348	348
query50	668	274	210	210
query51	3870	3741	3706	3706
query52	92	93	84	84
query53	212	218	169	169
query54	278	257	253	253
query55	79	78	76	76
query56	307	293	302	293
query57	1010	1005	965	965
query58	277	266	261	261
query59	2053	2234	2083	2083
query60	335	328	311	311
query61	170	140	144	140
query62	372	354	316	316
query63	194	165	160	160
query64	4961	1149	847	847
query65	3859	3652	3774	3652
query66	1457	420	307	307
query67	15775	15597	15512	15512
query68	2522	1065	742	742
query69	420	326	275	275
query70	974	946	977	946
query71	304	285	259	259
query72	5314	3210	3246	3210
query73	607	719	311	311
query74	8781	8808	8528	8528
query75	2288	2314	1906	1906
query76	2279	1051	636	636
query77	362	366	316	316
query78	9848	10131	9219	9219
query79	1055	894	590	590
query80	1519	522	437	437
query81	556	265	234	234
query82	1194	148	122	122
query83	345	262	240	240
query84	304	112	97	97
query85	1167	453	406	406
query86	414	300	288	288
query87	2846	2840	2870	2840
query88	3490	2556	2537	2537
query89	305	262	241	241
query90	1902	170	166	166
query91	168	159	135	135
query92	71	80	69	69
query93	1112	1010	650	650
query94	651	325	266	266
query95	579	392	322	322
query96	641	497	232	232
query97	2328	2387	2320	2320
query98	210	206	197	197
query99	615	562	512	512
Total cold run time: 246503 ms
Total hot run time: 173511 ms

[doris-robot]

ClickBench: Total hot run time: 26.66 s

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/clickbench-tools
ClickBench test result on commit 1c9675b2e81e98dcf9c889110fa326d6119c5a88, data reload: false

query1	0.05	0.05	0.05
query2	0.10	0.05	0.05
query3	0.26	0.08	0.09
query4	1.61	0.12	0.11
query5	0.28	0.26	0.25
query6	1.14	0.66	0.66
query7	0.03	0.02	0.03
query8	0.05	0.04	0.03
query9	0.56	0.51	0.50
query10	0.55	0.57	0.55
query11	0.14	0.10	0.10
query12	0.14	0.10	0.11
query13	0.60	0.58	0.59
query14	0.95	0.93	0.95
query15	0.80	0.76	0.79
query16	0.42	0.38	0.41
query17	0.99	1.06	1.04
query18	0.23	0.21	0.20
query19	1.95	1.86	1.82
query20	0.02	0.02	0.01
query21	15.43	0.25	0.14
query22	5.30	0.05	0.04
query23	15.99	0.27	0.10
query24	1.36	0.69	0.33
query25	0.06	0.05	0.06
query26	0.14	0.13	0.14
query27	0.06	0.11	0.06
query28	3.44	1.08	0.88
query29	12.58	3.93	3.12
query30	0.27	0.14	0.11
query31	2.82	0.62	0.39
query32	3.25	0.58	0.46
query33	2.98	2.98	3.08
query34	15.75	5.14	4.36
query35	4.48	4.49	4.43
query36	0.65	0.50	0.50
query37	0.11	0.07	0.06
query38	0.07	0.04	0.04
query39	0.04	0.03	0.03
query40	0.16	0.15	0.14
query41	0.09	0.03	0.03
query42	0.04	0.03	0.02
query43	0.05	0.04	0.04
Total cold run time: 95.99 s
Total hot run time: 26.66 s

[hello-stephen]

BE UT Coverage Report

Increment line coverage 100.00% (12/12) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	52.46% (19117/36441)
Line Coverage	35.83% (177605/495677)
Region Coverage	32.27% (137145/424998)
Branch Coverage	33.23% (59428/178813)

[hello-stephen]

BE Regression && UT Coverage Report

Increment line coverage 100.00% (12/12) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	71.46% (25524/35720)
Line Coverage	54.02% (267476/495145)
Region Coverage	51.54% (221389/429511)
Branch Coverage	53.03% (95233/179584)