Clean up attention request related user callout data
We've removed attention request related backend code, but we have existing data in user_callouts which needs to be cleaned up.
We need to remove user_callouts that has 47, 48 as they are removed in !95446 (diffs)
It seems to be slow to remove without an index so we may need to add a temporary index and remove after the release.
Related to !95446 (merged) and #366442 (closed)