Address review comments: revert timeout and telemetry_enabled changes

Per reviewer feedback on PR #734:

1. Revert timeout from 30s back to 900s (line 299)
   - Reviewer noted that with wait=False, timeout is not critical
   - The async nature and wait=False handle the exit speed

2. Revert telemetry_enabled parameter back to True (line 734)
   - Reviewer noted this is redundant given the early return
   - If enable_telemetry=False, we return early (line 729)
   - Line 734 only executes when enable_telemetry=True
   - Therefore using the parameter here is unnecessary

These changes address the reviewer's valid technical concerns while
keeping the core fixes intact:
- wait=False for non-blocking shutdown (critical for Issue #729)
- Early return when enable_telemetry=False (critical for Issue #729)
- All Issue #731 fixes (null-safety, __del__, documentation)

Signed-off-by: Madhavendra Rathore <madhavendra.rathore@databricks.com>

Author: msrathore-db

src/databricks/sql/telemetry/telemetry_client.py

@@ -296,7 +296,7 @@ def _send_telemetry(self, events):
                 url,
                 data=request.to_json(),
                 headers=headers,
-                timeout=30,
+                timeout=900,
             )
 
             future.add_done_callback(
@@ -731,7 +731,7 @@ def connection_failure_log(
         UNAUTH_DUMMY_SESSION_ID = "unauth_session_id"
 
         TelemetryClientFactory.initialize_telemetry_client(
-            telemetry_enabled=enable_telemetry,
+            telemetry_enabled=True,
             session_id_hex=UNAUTH_DUMMY_SESSION_ID,
             auth_provider=None,
             host_url=host_url,