Merge "Add unit tests checking MTU of interfaces are set." am: edbf34a182 am: 320207fcf1

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2335546

Change-Id: I0da6eeb8e1140c6a5a2016a23806329c40098f8b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>