Remove media3-only line from exoplayer2 `build.gradle` file

#minor-release

PiperOrigin-RevId: 470999044
(cherry picked from commit e285e707)

library/transformer/build.gradle

@@ -30,7 +30,6 @@ android {
     }
     }
 
 
     sourceSets {
     sourceSets {
-        androidTest.assets.srcDir '../test_data/src/test/assets/' //copybara:media3-only
         androidTest.assets.srcDir '../../testdata/src/test/assets/'
         androidTest.assets.srcDir '../../testdata/src/test/assets/'
         test.assets.srcDir '../../testdata/src/test/assets/'
         test.assets.srcDir '../../testdata/src/test/assets/'
     }
     }