Add media-linker-config to test media APEX

media-linker-config was not added to test media APEX, so test media APEX
was not visible from linker. This change adds media-linker-config to
test media APEX so Media APEX can keep visible from test environment.

Bug: 170592137
Test: media_e2e_tests passed from crosshatch
Change-Id: I29ec401bc019527c762a128daf681f60352434e4