Bump API_LEVEL so we can use androidx prebuilts am: ff4f656ad5 am: 2858714850

Original change: https://android-review.googlesource.com/c/platform/tools/metalava/+/2061258

Change-Id: I9d338e39c024b267808b42883dbb8f528f22ea3b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>