fix: handle TA db replication lag

[joseph-sentry]

since we've observed a bit of replication lag between the primary and the TA read replica i just want to ensure we make these important reads from the primary to avoid any read-after-write inconsistencies

[sentry]

🔍 Existing Issues For Review

Your pull request is modifying functions with the following pre-existing issues:

📄 File: services/test_analytics/ta_processor.py

Function	Unhandled Issue
ta_processor_impl	ReportSession.DoesNotExist: ReportSession matching query does not exist. app.tasks.test_resu... Event Count: 101

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[seer-by-sentry]

🚨 Sentry detected 1 potential issue in your recent changes 🚨

Lower risk findings

• Line 42, services/test_analytics/ta_processor.py

  • Verify ReportSession objects are consistently stored in the 'default' database.
  • This may cause issues similar to: #6544280426

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[codecov-notifications]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.74%. Comparing base (eae0b7d) to head (4e3521d).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1220   +/-   ##
=======================================
  Coverage   97.74%   97.74%           
=======================================
  Files         459      459           
  Lines       37296    37296           
=======================================
  Hits        36454    36454           
  Misses        842      842           

Flag	Coverage Δ
integration	42.72% <0.00%> (ø)
unit	90.80% <100.00%> (ø)

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