chore: remove React 16.4's obsolete React imports (#28571)

Signed-off-by: hainenber <dotronghai96@gmail.com>

superset-frontend/src/explore/components/RunQueryButton/RunQueryButton.stories.tsx

@@ -16,7 +16,6 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import React from 'react';
 import { RunQueryButton, RunQueryButtonProps } from '.';
 
 export default {

superset-frontend/src/explore/components/RunQueryButton/RunQueryButton.test.tsx

@@ -17,7 +17,6 @@
  * under the License.
  */
 
-import React from 'react';
 import userEvent from '@testing-library/user-event';
 import { render, screen } from 'spec/helpers/testing-library';
 import { RunQueryButton } from './index';

superset-frontend/src/explore/components/RunQueryButton/index.tsx

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-import React, { ReactNode } from 'react';
+import { ReactNode } from 'react';
 import { t } from '@superset-ui/core';
 import Button from 'src/components/Button';