engine: Fixing perfomance issue between VdsRunTimeInfo and RunVmCommandBase

After introducing atomic update, no need for special lock inside of
RunVmCommandBase.decreasePendingVms()
In order to keep functionality for delay: SynchronousQueue will be used.
The thread will stuck until time out or some other thread will add some object to queue

Change-Id: Ia6c6e26c79dc6c06c9621e1938ecd034e9ce7ec7
Signed-off-by: Michael Kublin <mkublin@redhat.com>