STYLE: prefer REGISTER/NO_REGISTER instead of true/false for IOobject

- self-documenting

tutorials/incompressible/pimpleFoam/laminar/contaminatedDroplet2D/makePerturbation/makePerturbation.C

@@ -132,7 +132,7 @@ int main(int argc, char *argv[])
             runTime,
             IOobject::MUST_READ,
             IOobject::NO_WRITE,
-            false
+            IOobject::NO_REGISTER
         )
     );
 

tutorials/incompressible/pimpleFoam/laminar/sloshing2D/makeWave/makeWave.C

@@ -128,7 +128,7 @@ int main(int argc, char *argv[])
             runTime,
             IOobject::MUST_READ,
             IOobject::NO_WRITE,
-            false
+            IOobject::NO_REGISTER
         )
     );