Test: Rewrite ResolverTest.KeepListeningUDP am: 1e4e64d9 am: eb4c9964 am: 9c622115 am: c280aa78 am: 21a1f702 am: d66b687a

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/2466320



Change-Id: I7ae87a3ed2edd13b4874f9fb29bbf6b9f8b83e19
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>