Remove underscores from tests names

I5532e140a603be222cb3ea1ae563638317c1d745 introduced some tests with
underscores in their names, which GoogleTest discourages. Theses aren't
(currently) harmful, but update them to conform to recommendations.

Bug: 269685949
Bug: 259407931
Test: ActiveDisplayRotationFlagsTest
Change-Id: Ia5dd12f4b7fc32758ad4cb79f1e3118c98fd9340