Merge "Add dns_helper_unit_test in TEST_MAPPING" into main am: ee734fd41e

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2749728

Change-Id: I3e33e5dcfbd16e7273b5c867cf81afe94b323168
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>