Remove unused onSaveAndNewClick function

The onSaveAndNewClick function was defined but never called anywhere in
the StudioEditPanel component. There is no "Save and New" button in the
UI that would invoke this function, causing a TypeScript lint error.

Changes:
- Remove onSaveAndNewClick function definition

This fixes the @typescript-eslint/no-unused-vars lint error at line 152.

ui/v2.5/src/components/Studios/StudioDetails/StudioEditPanel.tsx

@@ -149,11 +149,6 @@ export const StudioEditPanel: React.FC<IStudioEditPanel> = ({
     setIsLoading(false);
   }
 
-  async function onSaveAndNewClick() {
-    const input = schema.cast(formik.values);
-    onSave(input, true);
-  }
-
   function onImageLoad(imageData: string | null) {
     formik.setFieldValue("image", imageData);
   }