Merge branch 'michold-cleanup-epic' into 'master'

Clean up after epic events migration to internal events

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/141507



Merged-by: Max Fan <mfan@gitlab.com>
Approved-by: Hercules Merscher <hmerscher@gitlab.com>
Approved-by: Sebastian Rehm <srehm@gitlab.com>
Approved-by: Max Fan <mfan@gitlab.com>
Reviewed-by: Max Fan <mfan@gitlab.com>
Co-authored-by: michold <mwielich@gitlab.com>