perf: Assume yes when installing required packages in the GCE instance.
perf: Assume yes when installing required packages in the GCE instance.

BUG=None
R=stephana@google.com

Review URL: https://codereview.chromium.org/760623006

Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot