functionObject: change default behavior of 'end()' to do nothing rather than calling execute and write

Time: call functionObject 'execute()' and 'end()' for last time-step

Now the operation of functionObject 'end()' call is consistent between running and post-processing

src/OpenFOAM/db/Time/Time.C

@@ -850,11 +850,9 @@ bool Foam::Time::run() const
 
     if (!subCycling_)
     {
-        // only execute when the condition is no longer true
-        // ie, when exiting the control loop
         if (!running && timeIndex_ != startTimeIndex_)
         {
-            // Note, end() also calls an indirect start() as required
+            functionObjects_.execute();
             functionObjects_.end();
         }
     }

src/OpenFOAM/db/functionObjects/functionObject/functionObject.C

@@ -136,7 +136,7 @@ bool Foam::functionObject::read(const dictionary& dict)
 
 bool Foam::functionObject::end()
 {
-    return execute() && write();
+    return true;
 }