Keep PDF preview mounted while not visible (#21270)

GitOrigin-RevId: 266ecbb72a5238e1e977265e56c33880ec1a54be

services/web/frontend/js/features/ide-react/components/editor-and-pdf.tsx

@@ -103,7 +103,7 @@ export const EditorAndPdf: FC = () => {
         onExpand={handlePdfPaneExpand}
         className="ide-react-panel"
       >
-        {pdfIsOpen && <PdfPreview />}
+        <PdfPreview />
         {/* ensure that "sync to code" is available in PDF only layout */}
         {pdfLayout === 'flat' && view === 'pdf' && (
           <div className="synctex-controls" hidden>