SDK / exoplayer

This method is no longer needed since we added SubtitleConfiguration#id
in https://github.com/google/ExoPlayer/commit/59d98b9a4e2381647f3e4552b6935bcca1be6f89.

Issue: google/ExoPlayer#10016

PiperOrigin-RevId: 432169262
(cherry picked from commit 540f2061)