Fix merge mistake, wrong track type.

Fix mistake from the backport merge, should get TEXT track type for subtitles.  Also update testcase to match pattern in `dev-v2` branch.

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

@@ -462,7 +462,7 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
           variant = getVariantWithSubtitleGroup(variants, groupId);
           if (variant != null) {
             @Nullable
-            String codecs = Util.getCodecsOfType(variant.format.codecs, C.TRACK_TYPE_AUDIO);
+            String codecs = Util.getCodecsOfType(variant.format.codecs, C.TRACK_TYPE_TEXT);
             sampleMimeType = MimeTypes.getMediaMimeType(codecs);
             if (sampleMimeType == null) {
               sampleMimeType = MimeTypes.TEXT_VTT;

library/hls/src/test/java/com/google/android/exoplayer2/source/hls/playlist/HlsMasterPlaylistParserTest.java

@@ -364,7 +364,7 @@ public class HlsMasterPlaylistParserTest {
   }
 
   @Test
-  public void testSubtitleCodec() throws IOException {
+  public void parseMasterPlaylist_withMatchedTTMLSubtitleCodec() throws IOException {
     HlsMasterPlaylist playlistWithSubtitles =
             parseMasterPlaylist(PLAYLIST_URI, PLAYLIST_WITH_SUBTITLE_CODEC);
     HlsMasterPlaylist.Variant variant = playlistWithSubtitles.variants.get(0);