Camera: Don't hold locks during shared output dequeue

Blocking dequeue calls for async output surfaces seem to be
possible. Refactor the code so that stream splitter doesn't
hold any locks during output surface dequeue calls triggered
by buffer released callbacks.

Bug: 73953239
Test: Camera CTS
Change-Id: Ia2166de73d2b8de7ef4157e81c87f53c8a264c0c