add apex_available for networkstack_client am: d95b328a95 am: 7f9a4ac257 am: d44bddfb66

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/1587575

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: If00d8e8a9d8cedd40572c7db45dc95f8ab99231a