Add mediaroutertest to frameworks/base/media/TEST_MAPPING

This is a cherrypick of commit da497e609cc81d840ba5c46506be0a823b138646.

Bug: 232812007
Change-Id: I283df974d80e61cdf6997b8f58c2ff9e642961d5
Merged-In: I283df974d80e61cdf6997b8f58c2ff9e642961d5
Test: N/A. TEST_MAPPING change.
2 files changed