Fix hanging ExoPlayerPlaybackSeekTest

The test uses a video renderer to count the number of frames and could
time out if some frames were dropped.

PiperOrigin-RevId: 670181693

libraries/transformer/src/androidTest/java/androidx/media3/transformer/mh/performance/ExoplayerEffectPlaybackSeekTest.java

@@ -113,6 +113,18 @@ public final class ExoplayerEffectPlaybackSeekTest {
             }
             super.renderOutputBufferV21(codec, index, presentationTimeUs, releaseTimeNs);
           }
+
+          @Override
+          protected boolean shouldDropOutputBuffer(
+              long earlyUs, long elapsedRealtimeUs, boolean isLastBuffer) {
+            return false;
+          }
+
+          @Override
+          protected boolean shouldDropBuffersToKeyframe(
+              long earlyUs, long elapsedRealtimeUs, boolean isLastBuffer) {
+            return false;
+          }
         };
 
     instrumentation.runOnMainSync(