Fix Geo: Personal snippets not syncing

What does this MR do and why?

• Fixes syncing of personal snippets (they could not sync at all)
• I think this is also a minor fix for event creation for project snippets on update. (If I'm wrong about that, there is no consequence.)

MR acceptance checklist

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Configure Geo if not already done
2. Create a personal snippet
3. On master, Admin > Geo > Sites should show that snippet stuck in "Queued" or in the Replication Details > Snippet Repositories > filtered on "Started"
4. On this branch, in Admin > Geo > Sites > Replication Details > Snippet repositories you can click Resync all and it should become "Synced"

Related to #439933 (closed)