[Android Compile Server] Add "-f" to git checkout
[Android Compile Server] Add "-f" to git checkout

Change-Id: Ia70f4e4b62b305e60205fc03cd153d0a3fdab79d
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/218277
Reviewed-by: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@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