[automerger skipped] Fully setup test TUN iface on create. am: 5cbd7b38ca am: ac39fac427 -s ours

am skip reason: Merged-In I4c1262e566517bbb03dd610f595e4d18bc4e7735 with SHA-1 7a5fbc2b6e is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/14969443

Change-Id: I7fbbe2da9a0086da40a276c8d940fbf76d5b5b97