ENH: snappyHexMesh: early exit of leak detection. See #2403

Reverted edfault behaviour

tutorials/mesh/snappyHexMesh/sphere_gapClosure/system/snappyHexMeshDict

@@ -157,6 +157,9 @@ castellatedMeshControls
     // are only on the boundary of corresponding cellZones or also allow
     // free-standing zone faces. Not used if there are no faceZones.
     allowFreeStandingZoneFaces false;
+
+    // Enable automatic leak closure (default is exit immediately)
+    useLeakClosure true;
 }