Tests | Add Flaky test details to ConnectionFailoverTests

[cheenamalhotra]

There are some regularly failing tests from ConnectionFailoverTests class, this PR adds failures/error message details for further investigation.

[Copilot]

Pull request overview

Updates ConnectionFailoverTests (simulated server unit tests) to capture additional context about recurring flaky failures, aiming to aid later diagnosis of intermittent CI issues in failover scenarios.

Changes:

• Annotates existing flaky theories/facts with inline failure summaries (assert diffs, timeouts, and SqlException details).
• Adds TODO blocks near assertions/open calls to preserve observed failure output for investigation.
• Marks an additional theory (TransientFault_RetryDisabled_WithUserProvidedPartner_ShouldFail_NotFailover) as Category=flaky with a brief failure note.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.55%. Comparing base (bfbdd30) to head (8eb1089).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4341      +/-   ##
==========================================
- Coverage   66.69%   64.55%   -2.14%     
==========================================
  Files         284      279       -5     
  Lines       43238    66069   +22831     
==========================================
+ Hits        28836    42653   +13817     
- Misses      14402    23416    +9014     

Flag	Coverage Δ
CI-SqlClient	?
PR-SqlClient-Project	64.55% <ø> (?)

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