remove default finalizer name

Author: Soroosh Sarabadani

operator-framework/src/main/java/io/javaoperatorsdk/operator/api/Controller.java

@@ -17,7 +17,7 @@
 
     Class<? extends CustomResource> customResourceClass();
 
-    String finalizerName() default DEFAULT_FINALIZER;
+    String finalizerName();
 
     /**
      * If true, will dispatch new event to the controller if generation increased since the last processing, otherwise will