Merge "UpstreamNetworkMonitor: remove unused mTetheringUpstreamNetwork" am: 42d28f1d66 am: 7ba684cb07

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

Change-Id: I42b861c2ba4675297bef3fd600f8a2f624999024
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>