Fix chunkless preparation for playlists with dangling EXT-X-MEDIA tags

We are not able to associate a codecs attribute to an EXT-X-MEDIA tag if
there is no variant with a matching AUDIO GROUP-ID. Lack of codecs string
prevents chunkless preparation from determining the track type.

Issue: #7678
PiperOrigin-RevId: 324822415

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java

@@ -459,12 +459,12 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
             }
           }
           formatBuilder.setSampleMimeType(sampleMimeType);
-          if (uri == null) {
-            // TODO: Remove muxedAudioFormat and add a Rendition with a null uri to audios.
-            muxedAudioFormat = formatBuilder.build();
-          } else {
+          if (uri != null) {
             formatBuilder.setMetadata(metadata);
             audios.add(new Rendition(uri, formatBuilder.build(), groupId, name));
+          } else if (variant != null) {
+            // TODO: Remove muxedAudioFormat and add a Rendition with a null uri to audios.
+            muxedAudioFormat = formatBuilder.build();
           }
           break;
         case TYPE_SUBTITLES: