pulld: Turn on Prometheus and cloud logging on GCE.
pulld: Turn on Prometheus and cloud logging on GCE.

Also switch to using common.InitWithMust() on the GCE path.

BUG=skia:

Change-Id: Icf1b0e2f299c5ac2b479c3c61e45666d34c6260f
Reviewed-on: https://skia-review.googlesource.com/7024
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Commit-Queue: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@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