Merge "TetheringTest: replace upstream change check by event callback" am: 119e5adc14

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2383985

Change-Id: I2745b4b8f7e8a8065c7d39f58769de8520c83b0b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>