Disable subtitle output in the playback tests

This is currently flaky, so it's better to disable it than end up with
flaky tests.

PiperOrigin-RevId: 345436319

robolectricutils/src/main/java/com/google/android/exoplayer2/robolectric/PlaybackOutput.java

@@ -52,7 +52,7 @@ public final class PlaybackOutput implements Dumper.Dumpable {
     // player.getCurrentPosition() inside onMetadata/Cues will likely be non-deterministic
     // because renderer-thread != playback-thread.
     player.addMetadataOutput(metadatas::add);
-    player.addTextOutput(subtitles::add);
+    // TODO(internal b/174661563): Output subtitle data when it's not flaky.
   }
 
   /**

testdata/src/test/assets/playbackdumps/dash/webvtt-in-mp4.dump

@@ -31,28 +31,3 @@ MediaCodec (video/avc):
   buffers[28] = length 530, hash C98BC6A8
   buffers[29] = length 568, hash 4FE5C8EA
   buffers[30] = length 0, hash 1
-TextOutput:
-  Subtitle[0]:
-    Cues = []
-  Subtitle[1]:
-    Cue[0]:
-      text = This is the first subtitle.
-      textAlignment = ALIGN_CENTER
-      lineType = 1
-      lineAnchor = 0
-      position = 0.5
-      positionAnchor = 1
-      size = 1.0
-  Subtitle[2]:
-    Cues = []
-  Subtitle[3]:
-    Cue[0]:
-      text = This is the second subtitle.
-      textAlignment = ALIGN_CENTER
-      lineType = 1
-      lineAnchor = 0
-      position = 0.5
-      positionAnchor = 1
-      size = 1.0
-  Subtitle[4]:
-    Cues = []

testdata/src/test/assets/playbackdumps/mkv/sample_with_ssa_subtitles.mkv.dump

@@ -63,17 +63,3 @@ MediaCodec (video/avc):
   buffers[28] = length 476, hash A0423645
   buffers[29] = length 486, hash DDF32CBB
   buffers[30] = length 0, hash 1
-TextOutput:
-  Subtitle[0]:
-    Cues = []
-  Subtitle[1]:
-    Cue[0]:
-      text = This is the first subtitle.
-      textAlignment = ALIGN_CENTER
-      line = 0.95
-      lineType = 0
-      lineAnchor = 2
-      position = 0.5
-      positionAnchor = 1
-  Subtitle[2]:
-    Cues = []