Delete some obsolete test code.

- Get rid of obsolete annotations in MediaInserterTest.

- Drop support for @BrokenTest and @SideEffect. Nobody uses
  SideEffect and none of the tests that use this test runner
  (vm-tests-tf, essentially) use @BrokenTest.

Change-Id: Id73c4d4eda8031689f9263c85b563c29e635d446