[Provider Model] Non-carrier data usage settings UI change

- Change the title from “Wi-Fi data usage” to “Non-carrier data usage”
- Change the warning message from “Carrier data accounting may differ
from device accounting” to “Excludes data that is used by carrier
networks”
- Screenshot:
  https://screenshot.googleplex.com/3bicWHu7g5StH8R
  https://screenshot.googleplex.com/AqceQBtY4AqnuGH

Bug: 172788855
Test: manual test
Change-Id: Ic4d6e5dbb0b7d1d851f6cf033d400a7f780261ac