Add DDR tests in NetworkStackTests. am: ff4d6a3d3f am: 4e8539ca19

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

Change-Id: I2d10ea1924ced19ce76b770219b857300e645b5a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>