Handle neighbor lost event am: e600bef8f9 am: dab9bb4938 am: a108e9b47d

Original change: https://android-review.googlesource.com/c/platform/frameworks/opt/net/ethernet/+/1586426

Change-Id: Ic5a7f0485035462b017adf15c4ae1c5c1b5baa82
tree: bdf3d17fdec1457f863bcdfc26d9fa61a49be5ff
  1. service-t/
  2. tests/