SDK / exoplayer

Clearing the exception puts the SimpleDecoder into a silent failure
state - the decoder thread is dead (because decode() has returned
false) but it's still possible to queue buffers to the decoder (they
just never get decoded). This partially reverts
https://github.com/google/ExoPlayer/commit/4107375c9d21136090d0071b04a498024eec6a4c

Also always recreate the decoder when handling an error in TextRenderer

This ensures we can try and decode a later subtitle sample after
encountering a decode error. This behaviour is what nulling out the
exception in SimpleDecoder.flush() was trying to achieve. We need to
ensure we don't start passing data to the new decoder until we've
hit the next key frame, so we throw away any non-keyframe samples
inside TextRenderer#render().

Issue: #7590
PiperOrigin-RevId: 319785908