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

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



Change-Id: I7206f89198f4e9f1194f164992fee5d4776adf1b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>