Description of problem:
Following the fix of create snapshot with Cinder disks for failure flow, 
The child command callback does not call the parent any more, but it is
all being done through ConcurrentChildCommandsExecutionCallback.

For stateless VM, part of the logic is to create a stateless snapshot
which being called from RunVmCommand.

before introducing ConcurrentChildCommandsExecutionCallback the
end action was called from CreateCinderSnapshotCommand endCommand though now
running a stateless VM creates a stateless snapshot and leaves the snapshot in lock status.
    
Version-Release number of selected component (if applicable):


How reproducible:
100%

Steps to Reproduce:
1. Run a stateless VM with Cinder disk
2.
3.

Actual results:
The stateless snapshot is in lock status for ever.

Expected results:
The stateless snapshot should be created and the stateless VM should run

Additional info: