Fixed following code smells reported by SonarQube:

1) Remove this redundant jump.
 2) Remove this commented out code.
 3) Variables should not be shadowed.

web/pgadmin/tools/schema_diff/static/js/schema_diff_ui.js

@@ -860,7 +860,7 @@ export default class SchemaDiffUI {
           if (index === -1) self.sel_filters.push(filter);
         } else {
           $(filter_class).addClass('visibility-hidden');
-          if(index !== -1 ) delete self.sel_filters[index];
+          if(index !== -1 ) self.sel_filters.splice(index, 1);
         }
       }
     });