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

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

superset-frontend/plugins/plugin-chart-word-cloud/src/chart/WordCloud.tsx

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-import React from 'react';
+import { PureComponent } from 'react';
 import cloudLayout, { Word } from 'd3-cloud';
 import {
   PlainObject,
@@ -88,10 +88,7 @@ const MAX_SCALE_FACTOR = 3;
 // Needed to avoid clutter when shrinking a chart with many records.
 const TOP_RESULTS_PERCENTAGE = 0.1;
 
-class WordCloud extends React.PureComponent<
-  FullWordCloudProps,
-  WordCloudState
-> {
+class WordCloud extends PureComponent<FullWordCloudProps, WordCloudState> {
   static defaultProps = defaultProps;
 
   // Cannot name it isMounted because of conflict