Merge "Use 1500 as MTU in NetDiagnostics if MTU is unknown" am: 2b7f9ee649 am: 526d247405

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2618639

Change-Id: Id963faf4367876c7f7751ea4c1096affebe313c5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>