magit-log-unique-re: remove noise

Or rather don't insert any noise in
`magit-insert-unpushed-commits',
`magit-insert-unpulled-commits', and
`magit-insert-unpulled-or-recent-commits', so that we don't have
any noise to match in `magit-log-unique-re' and subsequently ignore.
magit-insert-unpulled-or-recent-commits: fixes