Merge "Add tethering IPv4 UDP forwarding test" am: 76bc75f0a2 am: 8003834727 am: 3b8bd6eca7

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1843121

Change-Id: I8d73c62fb77ebd10135b8e1ef2fa43b683d87afa