ctsm5.4.042: Move $nl_flags->{'use_hillslope'} to a more effective spot

[slevis-lmwg]

Description of changes

In particular I'm moving the line
$nl_flags->{'use_hillslope'} = $nl->get_value('use_hillslope');
from sub setup_logic_params_file in bld/CLMBuildNamelist.pm to sub setup_logic_hillslope (because it's called before setup_logic_params_file), in order to get the intended hillslope_fsat_equals_zero (i.e., .true.) when use_hillslope = .true..

Specific notes

Contributors other than yourself, if any:

CTSM issues resolved or otherwise addressed, if any:
Resolves #4030

If answers are expected to change, describe (delete this line otherwise):
Answers change for Hillslope cases only; the changes are greater than roundoff

Any user interface changes (namelist or namelist defaults changes)?
Now get the correct hillslope_fsat_equals_zero for use_hillslope = .true.

Testing planned or performed, if any:

• ./build-namelist_test.pl OK (2 expected fails)
• aux_clm on derecho OK (Hillslope cases DIFF from the baseline)

Requirements before merge:

• I have followed the CTSM contribution guidelines.
• The code in this PR branch builds with no errors.
• The code in this PR branch runs with no errors. Briefly describe tested configuration(s): aux_clm test-suite
• (c) I have not performed a scientific evaluation of the answer changes in hillslope cases.
• This PR (a) does not create a new need to update the documentation and the hillslope updates to the User's Guide have already been assigned.

[slevis-lmwg]

• aux_clm on derecho, submitted like this
  ./run_sys_tests -s aux_clm -g ctsm5.4.042 --skip-compare
  because I already did it the other way, where I compared but didn't generate.
  Had to resubmit two tests, the second 4 times so far:

SSPMATRIXCN_Ly5_Mmpi-serial.1x1_numaIA.I2000Clm60BgcCropQianRs.derecho_intel.clm-ciso_monthly
ERP_P64x2_D_Ld5.f10_f10_mg37.I1850Clm50Bgc.derecho_intel.clm-ciso--clm-matrixcnOn_ignore_warnings

• aux_clm on izumi: had to resubmit one test
  ERI_D_Ld20.f10_f10_mg37.I2000Clm50Fates.izumi_nag.clm-FatesCold