surfaceFilmModels: Renamed injection -> ejection

The injection models do not inject parcels into the film they specifically eject
parcels from the film and the name "injection" is very confusing and misleading
hence the logical rename injection -> ejection.

tutorials/lagrangian/buoyantReactingParticleFoam/hotBoxes/constant/surfaceFilmProperties

@@ -65,7 +65,7 @@ forces
     }
 }
 
-injection
+ejection
 {
     curvatureSeparation
     {
@@ -75,7 +75,7 @@ injection
         );
     }
 
-    drippingInjection
+    drippingEjection
     {
         cloudName    reactingCloud1;
         deltaStable  0;