CommitService: removed overkill logcmdutil

As the comment suggested, it was not necessary in this case,
and I am still wary of it (also lots of useless code running).

The resulting code would have been directly compatible with
Mercurial before and after 5.5
4 jobs for !113 with topic/default/cleanup in 2 minutes and 10 seconds (queued for 1 second)
latest merge request