Drm tests have moved to android.mediadrm.cts package.
As part of bug b/171226061 to separate DRM test
classes to enable better tracking of test failures
through the OWNERs files.
Also remove obsolete MediaPlayer2DrmTest to match
ag/15388921 once it is merged.
Test: atest CtsMediaDrmTestCases
Bug: 190625926
Change-Id: I906889b32ac6be2335757fc4e17ca4b695236b4a