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

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

superset-frontend/src/visualizations/TimeTable/FormattedNumber.tsx

@@ -16,7 +16,6 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import React from 'react';
 import { formatNumber } from '@superset-ui/core';
 
 interface FormattedNumberProps {

superset-frontend/src/visualizations/TimeTable/SparklineCell.tsx

@@ -17,7 +17,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import React from 'react';
+import { ReactNode } from 'react';
 import moment from 'moment';
 import {
   formatNumber,
@@ -45,7 +45,7 @@ interface Props {
   height: number;
   numberFormat: string;
   dateFormat: string;
-  renderTooltip: ({ index }: { index: number }) => React.ReactNode;
+  renderTooltip: ({ index }: { index: number }) => ReactNode;
   showYAxis: boolean;
   width: number;
   yAxisBounds: Array<number | undefined>;

superset-frontend/src/visualizations/TimeTable/TimeTable.jsx

@@ -16,7 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import React, { useMemo } from 'react';
+import { useMemo } from 'react';
 import PropTypes from 'prop-types';
 import Mustache from 'mustache';
 import { scaleLinear } from 'd3-scale';