Allow `required` property be conditional for release_aidl_use_unfrozen am:...

Allow `required` property be conditional for release_aidl_use_unfrozen am: 585564ca am: 65966d29

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/3099338



Change-Id: Id75755b06fd2ea72108f0aebf07d1e5e6fe70aa8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>