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

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

Change-Id: I4349a19d2407c87d281371b77f7c7edcd55a0364
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>