[Testing] use AndroidJUnit4 in new MobileDataPreferenceControllerTest

Diff: https://diff.googleplex.com/#key=OYsSkuGzJNkP
Test: atest -c MobileDataPreferenceControllerTest
Merged-In: I1a2d7b38023681f3db3320aa9f315109280cfbd0
Change-Id: Ica6625bb924ad0e813b4f9cdca62b0126b63214e
1 file changed