Merge "Optimize neighbor unreachability detection probe fallback." am: 1aecd5e878 am: e0f24af4f5 am: 66d744cf12

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/1690573

Change-Id: Ifd0cb6918d40aa613538f1c36913103537548fc5