feat(grouping): Update outdated grouphash metadata

[lobsterkatie]

When we first introduced grouphash metadata, we were only collecting it for new hashes. Then, we started adding it to existing hashes which were missing it. This represents the final part of the process: updating metadata for grouphashes which already have it if the data we collect has changed since we last did so. Like backfilling missing grouphash metadata, this is controlled by the grouping.grouphash_metadata.backfill_sample_rate option.

[codecov]

Codecov Report

Attention: Patch coverage is 73.97260% with 19 lines in your changes missing coverage. Please review.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/sentry/models/grouphashmetadata.py	13.63%	19 Missing ⚠️

Additional details and impacted files

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##           kmclb-add-schema-version-to-grouphash-metadata-table   #85301      +/-   ##
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