[automerger skipped] [DO NOT MERGE] Add reasonable defaults to RBE...

[automerger skipped] [DO NOT MERGE] Add reasonable defaults to RBE configuration parameters. am: 19c39230 am: 6f14c848 -s ours am: 9c7aa6ce -s ours

am skip reason: Change-Id Ic66ad2b89866a67008950035bc3b559dae4e3a3e with SHA-1 54814ca5 is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/soong/+/12595315

Change-Id: I557588c7517fb028a493836b2957d4ec2e582593