[automerger skipped] Add CTS for registerBestMatchingNetworkCallback am: 512efafd32 -s ours

am skip reason: Merged-In I81abc1742a3aa965b444d0196f4eaa2393dcad1c with SHA-1 eb5451dd35 is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/14673220

Change-Id: I50a026db782a305e24694e65d05c0d0d320cdbdc