Merge "Add new arg "--gce-metadata" to record extra data for GCE instance." am: 1c268fe3f2

Original change: https://android-review.googlesource.com/c/platform/tools/acloud/+/1556110

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Iff84b11218dc97f1b7e72e67a484f0ee2cfa6c6f