multiValveEngineState: Execute at start with the clearance initialised to 0

Alternative resolution of bug-report https://bugs.openfoam.org/view.php?id=4054

src/fvMeshMovers/multiValveEngine/multiValveEngineState/multiValveEngineState.H

@@ -125,13 +125,6 @@ public:
             return wordList::null();
         }
 
-        //- Do not execute at the start of the run
-        //  as the clearance is not available at that point
-        virtual bool executeAtStart() const
-        {
-            return false;
-        }
-
         //- Execute, currently does nothing
         virtual bool execute();
 

src/fvMeshMovers/multiValveEngine/piston.C

@@ -100,7 +100,7 @@ Foam::fvMeshMovers::multiValveEngine::pistonObject::pistonObject
 :
     movingObject(name, engine, dict),
     bore_(bore()),
-    clearance_(great)
+    clearance_(0)
 {}