fix(worker): Resolve N+1 query in ProcessFlakesTask

[sentry]

This PR addresses an N+1 query performance issue within the ProcessFlakesTask by optimizing how Testrun objects are fetched.

Previously, process_flakes_for_commit would iterate through ReportSession objects (uploads), and for each upload, it would execute a separate database query to fetch its associated Testrun objects. This led to an N+1 query pattern, where N is the number of uploads for a given commit.

To resolve this, the following changes were made:

• Introduced a new helper function, get_testruns_for_uploads, which fetches all relevant Testrun objects for a list of uploads in a single batched database query.
• Modified process_single_upload to accept a pre-fetched list of Testrun objects, eliminating its internal get_testruns call when pre-fetched data is provided.
• Updated process_flakes_for_commit to utilize get_testruns_for_uploads to fetch all Testrun objects upfront and then pass the relevant subset to process_single_upload for each iteration.

This change significantly reduces the number of database queries, improving the performance of the ProcessFlakesTask.

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Fixes WORKER-YYP

[codecov]

Codecov Report

❌ Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 91.88%. Comparing base (701e991) to head (79ce67b).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...orker/services/test_analytics/ta_process_flakes.py	91.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1415      +/-   ##
==========================================
- Coverage   91.89%   91.88%   -0.01%     
==========================================
  Files        1325     1325              
  Lines       50868    50877       +9     
  Branches     1626     1626              
==========================================
+ Hits        46744    46750       +6     
- Misses       3818     3821       +3     
  Partials      306      306              

Flag	Coverage Δ
workerintegration	58.53% <8.33%> (-0.03%)	⬇️
workerunit	90.36% <91.66%> (-0.02%)	⬇️

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[codecov-notifications]

Codecov Report

❌ Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...orker/services/test_analytics/ta_process_flakes.py	91.66%	1 Missing ⚠️

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