Merge "Return false when tetherOffloadRuleAdd doesn't really add items" into main am: c694c351c0

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3252331

Change-Id: Icdef63341b27da81ac477907b60c99f7975d929f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>