Feat: Restore the button's background color #3221 (#9307)

### What problem does this PR solve?

Feat: Restore the button's background color #3221
### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/pages/dataset/testing/testing-form.tsx

@@ -98,10 +98,7 @@ export default function TestingForm({
             <FormItem>
               <FormLabel>{t('knowledgeDetails.testText')}</FormLabel>
               <FormControl>
-                <Textarea
-                  {...field}
-                  className="bg-colors-background-inverse-weak"
-                ></Textarea>
+                <Textarea {...field}></Textarea>
               </FormControl>
 
               <FormMessage />