Merge "Move test URL keys to NetworkStackConstants" am: efe44694a6

Original change: https://android-review.googlesource.com/c/platform/frameworks/libs/net/+/2104025

Change-Id: I4b430b9092629c4f694a535042d3caf58e5f55a9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>