Add CtsNetTestCases to TEST_MAPPING am: ad380c1de6 am: 94358c4c9e am: fa0aea21e2

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1612014

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ieeb84e2d6855d18448e34fbdb6bea58412158647