android: Allow running some singletons in parallel. am: e59c0db5 am: bef24e82

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2593066



Change-Id: I89dfe7e687e875914da3a91dea371c646b1f4c72
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>