[automerger skipped] [DO NOT MERGE] Add RBE support for Javac, R8, and D8 if...

[automerger skipped] [DO NOT MERGE] Add RBE support for Javac, R8, and D8 if respective env vars are set. am: c9a030aa am: 5507116c -s ours am: 33466e38 -s ours am: d9815534 -s ours

am skip reason: subject contains skip directive

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/12468474

Change-Id: Ida6e0a18eb781f241f9d420ed1f15511a190c403