Support partial module variants with apex_contributions am: 972917d7 am: cbebb343

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2978138



Change-Id: I3b328671143a2e73202614d458a533fa6a4e056d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>