mpegtsbase: Search SCTE-35 DRF_ID_CUEI in multiple registration descriptors

There are streams in the wild that have to add a SCTE-35 trigger in another e.g. GA94 stream. Most encoders would replace the GA94 descriptor ID with the CUEI one temporarily, but there are some that will add two registration ID descriptors, one with GA94 and one with CUEI.

Failing to parse the CUEI registration ID in that case would return FALSE in _stream_is_private_section , therefore setting it as known PES and pushing packets downstream instead of calling handle_psi.