Replace AbstractClient::doPerformInteractiveMoveResize() with a simpler solution
AbstractClient::doPerformInteractiveMoveResize() is only used by the X11Client to reset a boolean flag when the client doesn't support sync counters.
X11Client can call performInteractiveMoveResize() only in two cases: the sync request timer expires or the client increments the sync counter.
This change removes the AbstractClient::doPerformInteractiveMoveResize() function and adds a function to handle the case where the sync timer expires explicitly. This removes a virtual function in the AbstractClient and makes code more readable.