Jujutsu now creates colocated repositories by default (repositories which can be treated as either jj or git repos), and the `remote_bookmarks` template method is now returning the git-tracking bookmark in addition to the real remote ref name. This broke the remote bookmark detection because we were now getting results as "main@origin main@git" instead of just "main@origin", which didn't parse correctly when passed in to other commands. This change fixes this by updating the commands that fetch remote bookmarks to filter out the "git" remote from the results. Things which expect to fetch a single result will now also split lines and choose the first result. In practice what was there before should be fine after the filter change, but I'd rather be cautious. Testing Done: Unit tests pass again.