refactor: remove spec class since it's not really needed

Author: metacosm

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/informereventsource/InformerEventSourceTestCustomResource.java

@@ -12,7 +12,7 @@
 @Kind("Informereventsourcesample")
 @ShortNames("ies")
 public class InformerEventSourceTestCustomResource extends
-    CustomResource<InformerEventSourceTestCustomResourceSpec, InformerEventSourceTestCustomResourceStatus>
+    CustomResource<Void, InformerEventSourceTestCustomResourceStatus>
     implements Namespaced {
 
 }