Add DDR tests in NetworkStackTests. am: ff4d6a3d3f

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/2705015

Change-Id: Ia19f2164cacbe1a4974233b73db05e06f7a218ba
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>