Remove duplicate MediaRouter2 related tests

Since we copied the tests to CTS, this CL removes duplicate tests
under frameworks/base/media/tests.

Bug: 148572935
Test: atest mediaroutertest (it only runs MediaRouterManagerTest)
Change-Id: I1ef6a808dc42ac3e9b3f3a895dbe9128ae5d4ba6
4 files changed