Add an OWNERS_core_networking_xts for CTS/GTS/... and use it. am: 7aac4ad2f7

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1952105

Change-Id: Iab7fb8a5f9357fc6afeb150aaaab69e73c6aa5d4