refactor: Removes the deprecated ENABLE_EXPLORE_DRAG_AND_DROP feature flag (#26343)

superset-frontend/src/explore/components/controls/DndColumnSelectControl/DndColumnSelect.test.tsx

@@ -16,7 +16,6 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import { FeatureFlag } from '@superset-ui/core';
 import React from 'react';
 import { render, screen } from 'spec/helpers/testing-library';
 import {
@@ -32,14 +31,6 @@ const defaultProps: DndColumnSelectProps = {
   actions: { setControlValue: jest.fn() },
 };
 
-beforeAll(() => {
-  window.featureFlags = { [FeatureFlag.ENABLE_EXPLORE_DRAG_AND_DROP]: true };
-});
-
-afterAll(() => {
-  window.featureFlags = {};
-});
-
 test('renders with default props', async () => {
   render(<DndColumnSelect {...defaultProps} />, {
     useDnd: true,