This commit fixes an SQL syntax error in
`UserBadge.update_featured_ranks!` when
the `user_ids` param is an empty array `[]`.
This was causing the `Jobs::BackfillBadge` job to raise the following
exceptions:
```
Job exception: ERROR: syntax error at or near ")"
LINE 6: AND user_id IN ()
```
This commit fixes the same error in
`UserState.update_distinct_badge_count` as well
Follow-up to 3e4eac0fed05daedcdea50d6275e143469d55eda
62c6ee0de7