fix(data table): filter issue in expansion table (#11438)

### Related Ticket(s)

Closes #11179

### Description

For expansion table, filtering doesn't include the content in the expanded row.


### Changelog

**Changed**

- Updated the filter function to check the expanded row.

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packages/carbon-web-components/src/components/data-table/table.ts

@@ -236,10 +236,16 @@ class CDSTable extends HostListenerMixin(LitElement) {
   private _handleFilterRows() {
     const unfilteredRows = [] as any;
     forEach(this._tableRows, (elem) => {
-      const rowText = elem.textContent?.trim();
-      const filtered = this.filterRows(rowText as string, this._searchValue);
+      let rowText = elem.textContent?.trim();
+      let filtered = this.filterRows(rowText as string, this._searchValue);
       (elem as any).filtered = filtered;
 
+      if (filtered && this.expandable) {
+        rowText = (elem as any).nextElementSibling.textContent?.trim();
+        filtered = this.filterRows(rowText as string, this._searchValue);
+        (elem as any).filtered = filtered;
+      }
+
       if (!filtered) {
         unfilteredRows.push(elem);
       }