[QS] Update mobile tile secondary text

Since the mobile data string is required for the content description,
adding a new string for the short version and updating the footer impl
and icon setup logic to reference the content description instead.

Test: Manually, via string check in QS
Bug: 77693344
Change-Id: I794500bcd445f98d69c096f6bf2f3b7d147c2780
4 files changed