feat(grouping): Store metadata for new grouphashes

[lobsterkatie]

As part of the rollout of the new grouphash metadata table, this creates a GroupHashMetadata row for every new GroupHash we create. It's gated by a killswitch, and doesn't do much yet - the only data in the table so far is a creation timestamp - but this should give us a sense of whether or not there's going to be any hit to ingest DB performance.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:white_check_mark: All tests successful. No failed tests found.

Additional details and impacted files

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+ Hits       239608   239621   +13     
+ Misses      60358    60355    -3     
- Partials     6406     6408    +2     

[lobsterkatie]

talked during meeting, should ramp up writes slowly just to be safe

Yup - you beat me by about two minutes. 🙂 Just pushed it again, including a feature flag.

UPDATE: Here's the PR with the actual config: https://github.com/getsentry/sentry-options-automator/pull/2189.