[WifiTetheringTest] Use LinkProperties APIs for default IPv6 route

Bug: 70530304
Test: Verified the changes
Change-Id: Ia12877d1d04301b466a474f94cc01e44be90a4a1
1 file changed
tree: 6f14beb39ec2c7fcc42986f895a2420eeffaa5e1
  1. acts/
  2. tools/
  3. wts-acts/
  4. Android.mk
  5. PREUPLOAD.cfg