Use git from CIPD for docker_pushes_watcher
Use git from CIPD for docker_pushes_watcher

Bug: skia:9514
Bug: skia:9538
Change-Id: I7ea3e6ea15e592c2512253802336c0cc90b7bb95
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/261742
Reviewed-by: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>
Commit-Queue: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot