Set will-change: transform on PDF canvas container (#25153)

GitOrigin-RevId: 316a99ac99cbff321fc2ae5a737d0aaf134ff775

services/web/frontend/stylesheets/bootstrap-5/pages/editor/pdf.scss

@@ -193,6 +193,7 @@
     div.pdf-canvas {
       background: white;
       box-shadow: 0 0 10px rgb(0 0 0 / 50%);
+      will-change: transform;
     }
 
     div.pdf-canvas.pdfng-empty {