Add servicetests/media to TEST_MAPPING

This change adds all tests under servicetests/media to presubmit for
changes under android/server/media.

Bug: 244312001
Test: cd frameworks/base/services/core/java/com/android/server/media &&
atest

Change-Id: I5de7e1d98f8ec12b7e7cf6e933003b76e23eac40