Copilot Search a11y: use div instead of header for overlay (#55924)

Author: Ebonsignori

src/search/components/input/SearchOverlay.tsx

@@ -4,7 +4,6 @@ import { useRouter } from 'next/router'
 import {
   ActionList,
   Box,
-  Header,
   IconButton,
   Link,
   Overlay,
@@ -698,7 +697,7 @@ export function SearchOverlay({
         aria-labelledby={overlayHeadingId}
         ref={overlayRef}
       >
-        <Header className={styles.header}>
+        <div className={styles.header}>
           <Box
             sx={{
               display: isAskAIState ? 'flex' : 'none',
@@ -761,7 +760,7 @@ export function SearchOverlay({
               </Stack>
             }
           />
-        </Header>
+        </div>
         <ActionList.Divider
           sx={{
             display: inErrorState ? 'none' : 'block',