sync-server: Avoid decoding in the server pipeline if possible
sync-server: Avoid decoding in the server pipeline if possible

We just need the pipeline as a dummy to keep track of base time, seek
position, etc. So now we try to stop uridecodebin from plugging anything
in after a parser (or not even that, if the container provides framed
buffers).

ford-prefect/gst-sync-server,ford-prefect/gst-sync-server