fix(worker): Eliminate N+1 queries in ProcessFlakesTask

[sentry]

This PR addresses an N+1 query issue within the app.tasks.flakes.ProcessFlakesTask by implementing two key changes:

1. Bulk fetching Testruns: Previously, process_single_upload would execute a separate database query to fetch Testrun objects for each ReportSession within a loop. This has been refactored to use a new get_testruns_for_uploads function, which fetches all relevant Testrun objects for all uploads in a single batched query. These are then grouped in memory and passed to process_single_upload.
2. Batch updating expired Flakes: When a flake reached 30 consecutive passes and expired, an individual flake.save() call was made. This has been changed to collect all such expired flakes into a list, which is then updated in a single Flake.objects.bulk_update() call after all uploads have been processed.

These changes significantly reduce the number of database queries executed by the task, improving performance and reducing database load.

Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. In 2022 this entity acquired Codecov and as result Sentry is going to need some rights from me in order to utilize my contributions in this PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

Fixes WORKER-YTY

[codecov]

Codecov Report

❌ Patch coverage is 94.73684% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 91.88%. Comparing base (e682d07) to head (8882c33).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...orker/services/test_analytics/ta_process_flakes.py	94.73%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1228      +/-   ##
==========================================
- Coverage   91.89%   91.88%   -0.01%     
==========================================
  Files        1325     1325              
  Lines       50868    50880      +12     
  Branches     1626     1626              
==========================================
+ Hits        46744    46753       +9     
- Misses       3818     3821       +3     
  Partials      306      306              

Flag	Coverage Δ
workerintegration	58.53% <15.78%> (-0.04%)	⬇️
workerunit	90.36% <94.73%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

[codecov-notifications]

Codecov Report

❌ Patch coverage is 94.73684% 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	94.73%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.