fix(material-angular-io): update site images (#30543)

The site images, e.g. when linking the docs site on social media, were still using the M2 appearance. These changes update the images and delete some unnecessary ones.

Author: crisbeto

material.angular.io/scenes/src/app/scene-viewer/scene-viewer.scss

@@ -13,4 +13,5 @@ app-scene-viewer {
   top: 0;
   height: 100%;
   width: 100%;
+  pointer-events: none;
 }