Reduce flakiness of GL release test

Based on experimentation it seems that buffers can occasionally (roughly 1% of test runs) be dropped when rendering off-screen from EGL on the emulator. Specifically, in this test, sometimes after rendering three buffers with distinct timestamps only the first and third buffers' timestamps are handled in the `ImageReader`'s image available callback causing the assertion checking all frames rendered to fail. This behavior seems to be independent of the nanosecond presentation time attached to the buffers (as expected for off-screen rendering).

Introducing a pause of 1 second between rendering each frame reduces the flake rate to around 1/2000. This increases the run time of some of the tests, so this change also removes the 5 second `FRAME_PROCESSING_WAIT_MS` (it seems to be unnecessary when rendering off-screen) and instead uses a latch to wait until the frame processor has handled 'end of stream'.

PiperOrigin-RevId: 499440591

library/effect/src/main/java/com/google/android/exoplayer2/effect/GlEffectsFrameProcessor.java

@@ -25,6 +25,7 @@ import android.opengl.EGLContext;
 import android.opengl.EGLDisplay;
 import android.view.Surface;
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 import androidx.annotation.WorkerThread;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.util.DebugViewProvider;
@@ -366,6 +367,12 @@ public final class GlEffectsFrameProcessor implements FrameProcessor {
     previousStreamOffsetUs = C.TIME_UNSET;
   }
 
+  /** Returns the task executor that runs frame processing tasks. */
+  @VisibleForTesting
+  /* package */ FrameProcessingTaskExecutor getTaskExecutor() {
+    return frameProcessingTaskExecutor;
+  }
+
   @Override
   public Surface getInputSurface() {
     return inputSurface;