Add test for tetherOffloadRule4Clear am: fa3942c7e7

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1838894

Change-Id: I37e340e4cebeb252c9a02ce7f7c21253fb835ebc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>