progress: always show done message

The done message was omitted if the task is shorter than 0.5s. This
might confuse users.

Bug: b/371638995
Change-Id: I3fdd2cd8daea16d34fba88457d09397fff71af15
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/440222


Tested-by: Kuang-che Wu <kcwu@google.com>
Commit-Queue: Kuang-che Wu <kcwu@google.com>
Reviewed-by: Josip Sokcevic <sokcevic@google.com>