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 and processed.

Changes Made:

• Replaced the individual get_testruns(upload) calls within the process_flakes_for_commit loop with a single bulk fetch (get_testruns_for_uploads) for all relevant uploads.
• Testruns are now grouped by upload_id in memory after the bulk fetch, eliminating repeated database queries inside the loop.
• Modified handle_pass to collect expired Flake objects into a list, deferring their database updates to a single Flake.objects.bulk_update call at the end of process_flakes_for_commit.
• Ensured all relevant fields (end_date, count, recent_passes_count) are updated for expired flakes during the bulk update.

These changes significantly reduce the number of database queries executed when processing flakes, improving the performance and efficiency of the ProcessFlakesTask.

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Fixes WORKER-YZ0

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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 91.89%. Comparing base (701e991) to head (e0c0e10).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1430   +/-   ##
=======================================
  Coverage   91.89%   91.89%           
=======================================
  Files        1325     1325           
  Lines       50868    50875    +7     
  Branches     1626     1626           
=======================================
+ Hits        46744    46751    +7     
  Misses       3818     3818           
  Partials      306      306           

Flag	Coverage Δ
workerintegration	58.54% <17.64%> (-0.02%)	⬇️
workerunit	90.38% <100.00%> (+<0.01%)	⬆️

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