Drop MctsMediaRouterTestCases The Cts/Mcts split was carried across when decomposing MediaBetterTogetherTestCases. However all of the tests that landed in router are framework-specific; the mix of framework/module all landed in the other MediaSession tests. Bug: 397770696 Flag: EXEMPT test fix Test: build, ensure that MctsMediaRouterTestCases is not present Change-Id: Ib09137d3dcdc1a652ef2925ad4c419e22b810f3e