Revert "Death to synchronous transactions (1/2)"

This reverts commit c6a607aa.

It causes issues when resizing: default buffer size on the consumer side
only gets set when the transaction actually executes. But because
consumer is not blocked on SF over WM anymore, it gets the default
buffer size before the surface is resized, and thus uses wrong bounds
for the buffer to be drawn, and never submits another one.

This needs a more involved fix.

Bug: 28122036
Bug: 28128613
Change-Id: I0e738f99e43fc9ea25426e9e6e607e01413d3bb7