Duplicate/Repeated letters in CEA-608 Dash captions

### ExoPlayer Version

2.17.1

### Devices that reproduce the issue

* Pixel 2 running Android 11
* Has happened on every other emulator, device we've tried as well

### Devices that do not reproduce the issue

_No response_

### Reproducible in the demo app?

Not tested

### Reproduction steps

1. Setup ExoPlayer with a StyledPlayerView
2. Play a DASH DRM stream with CEA-608 track (ex. https://content.uplynk.com/a0860f48bb8544f5bed2c40d5cc14663.mpd?start=2600&stop=2900), with this license server URL: https://content.uplynk.com/wv
3. Enable any of the caption tracks (e.g. EN)
4. Observe captions on screen

### Expected result

Captions display correctly.

### Actual result

Observe the captions being displayed with many instances of duplicated letters.

We're not experiencing this on other platforms/players we've tried with the same streams (ex. captions display fine on https://bitmovin.com/demos/drm).

I believe this is the same issue documented here: https://github.com/google/ExoPlayer/issues/9135.

### Media


Media URL: https://content.uplynk.com/a0860f48bb8544f5bed2c40d5cc14663.mpd?start=2600&stop=2900
Widevine License Server URL: https://content.uplynk.com/wv