fix: Add caps to celery work

[suejung-sentry]

[UPDATE - this PR as is won't work unless I keep track of the start somewhere durable.. thinking.. tbd]

This PR removed bounds from cleanup_flare() function, causing it to process potentially millions of records instead of limited batches. This created too many concurrent file/socket connections (redis, postgres, GCS), exceeding the system's file descriptor limit (ulimit), resulting in "Error 24: Too many open files" in Celery.

Fix: Added back bounded processing (max 200 batches per run), used .iterator() for memory efficiency, and added throttling (time.sleep(0.005)) between file deletions to prevent connection spikes. Note that this means it will take more daily jobs to pay down the rows needing cleanup, but we'll do it in more manageable batches.

Also note this PR retains the changes that the original above PR was meant to solve (i.e., look at everything instead of just ids # 5000-500000, so we correctly process 1-4999 and 500001+).

Closes https://linear.app/getsentry/issue/CCMRG-1352/fix-ongoing-intermittent-celery-task-failures-reported-issue

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.32%. Comparing base (f97b2d3) to head (efe0edb).

❗ Current head efe0edb differs from pull request most recent head 4928645

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✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #301   +/-   ##
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  Coverage   94.32%   94.32%           
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  Files        1228     1228           
  Lines       45278    45286    +8     
  Branches     1441     1441           
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+ Hits        42709    42717    +8     
  Misses       2268     2268           
  Partials      301      301           

Flag	Coverage Δ
workerintegration	61.57% <4.76%> (-0.03%)	⬇️
workerunit	90.61% <100.00%> (+<0.01%)	⬆️

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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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[suejung-sentry]

Hmmm actually this totally won't work unless I persist the start somewhere durable. Maybe need to write a postgres table for this... will think about it