playsink: use queue to avoid lock in audiotee audio branches

playsink: use queue to avoid lock in audiotee audio branches

This part of pipeline is:

tee name=t ! visualizationbin ! streamsynchronizer name=s
t. ! s.

streamsynchronizer might block and it could starve the visualization
branch of the pipeline when it is enabled.

The visualization bin has queues internally but the other branch
that links the audiotee directly to the synchronizer is vulnerable
to block. Adding a queue between "t. ! s." fixes deadlocks.

https://bugzilla.gnome.org/show_bug.cgi?id=749676