Move TestBoundariesUserAction(Tool) to G4DebuggingTools
Following !51707 (merged). The TestBoundariesUserAction
and the accompanying AlgTool are the last classes in the
Simulation/ISF/ISF_Geant4/ISF_Geant4UserActions
. This user action has nothing ISF-specific about it, so
it made more sense to move it to the G4DebuggingTools
package and remove the now empty Simulation/ISF/ISF_Geant4/ISF_Geant4UserActions
package from the release.