Remove the ability for users to lock ratings, note, and post statuses.
Historically the majority of locked posts were from 10+ years ago when
certain users habitually locked ratings and notes on every post they
touched for no reason. Nowadays most posts have been unlocked. Only a
handful of locked posts are left, none of which deserve to be locked.
The is_rating_locked, is_note_locked, and is_status_locked columns still
exist in the database, but aren't used.
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