Migrate DnsUtilsTest to the NetworkMonitor version of FakeDns. am: 9cef6de3bd am: b8a62bd170

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/3261832

Change-Id: I7e5c0f984c50d573207b313cae1ba1ca10749fbc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>