3rdparty/cloud: Minor cleanup to gcp sysprep script

Change-Id: I64081e18ebb64b58223b5f693339d82820bb6ccb
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7087
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

3rdparty/google: add script for making Google Compute Engine images

Change-Id: Ia52b8e6a30255ee7903cfb0834d4030b6774b1c8
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5963
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>