Retain properly attributed activity log events for expired/revoked project/group access token activity

Proposal

When a project/group access token is revoked or expired, the associated bot account is deleted.

This removes its activity from the activity log (events table). It also reassigns its assignments to the Ghost user, which is the topic of DUPLICATE: Indicate PAT action is from revoked ... (#276496 - closed)

(Deactivating the accounts rather than deleting them would tackle the Ghost User issue and the activity log.)

*⃣ activity log BEFORE deleting token

*⃣ activity log AFTER deleting token