SDK / exoplayer

- Call onDisabled last. onDisabled really shouldn't be doing
  anything with the stream, so pretty sure this is fine (and
  guarantees the stream is cleared properly even if onDisabled
  throws a RTE).
- Remove super.onDisabled calls from Text/Metadata renderers.
  This is just for consistency; we don't make such calls in
  other direct descendants of BaseRenderer.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=156130640