[autorollers] Delete .repo dir before resyncing after a sync failure
[autorollers] Delete .repo dir before resyncing after a sync failure

No idea why this happens but deleting .repo seems to fix it.

Bug: skia:12146
Change-Id: I6c12fc7c6aa6b64e4b892410451e0899dbe2e295
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/430421
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