The migration was removing all but one 'on_holiday' user custom field...
Not big deal though since that custom field is being (re)set regularly in the 'update_holiday_usernames' job.
- FIX: update_holiday_usernames wasn't deleting "on_holiday" user custom fields
when no users were on holiday
- FIX: flair wasn't working on mentions when using subfolder
- PERF: only decorateCooked and addPosterIcon if there's at least one user on holiday
- Migration to remove duplicate "on_holiday" user custom fields
- Add unique index for the "on_holiday" user custom field
- Localize the "On Holiday" title
- Add the boolean type to the "on_holiday" user custom field