[automerger skipped] Merge "Set RBE_DIR default value to point to prebuilts in...

[automerger skipped] Merge "Set RBE_DIR default value to point to prebuilts in tree." into rvc-dev am: 461c0d46 am: b1a9ea09 -s ours

am skip reason: Change-Id I3392a0f7ac6de818d0c5ba2e113fcb035c6fa0ae with SHA-1 83c95dea is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/12445424

Change-Id: Iae5e7107f49d78093d093f8bd40df697604de45c