progress/sync: include active number of jobs

Provide a bit more info to users that things are actively running.

Bug: https://crbug.com/gerrit/11293
Change-Id: Ie8eeaa8804d1ca71cf5c78ad850fa2d17d26208c
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/297904


Reviewed-by: Michael Mortensen <mmortensen@google.com>
Tested-by: Mike Frysinger <vapier@google.com>