Change TetheringConstants class to final

Bug: 151322331
Test: m doc-comment-check-docs

Change-Id: Ieca36d81b7799988b8dbb9c0d22de690136303ab
Merged-In: Ia02be3d1d91a08ae4a56b25560ed448c96a693db
(cherry picked from commit 5e2740b24658ba340a6b47a46c89cfd642afe394)
2 files changed