Silence duplicate DNS prefetch requests am: 03bc8ba02d am: 58ab2bb08b am: 5c433615fd am: 3976919c4f

Original change: https://android-review.googlesource.com/c/platform/packages/services/Iwlan/+/2168869

Change-Id: Iee4307fc94b6eeb2ea4f3d89895deec9a876755b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>