Merge "UpstreamNetworkMonitor: remove unused mTetheringUpstreamNetwork" am: 42d28f1d66 am: 7fb5392945 am: 4918283bfc

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2383987

Change-Id: Ie7058d75c48e964e6a4b499f59652ec3f34bb428
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>