Fix review panel header positioning in Firefox and Safari (#20995)

* Fix review panel header positioning in Firefox and Safari

* update scss

GitOrigin-RevId: 5427f91f077104639a72f608c8d7572ab7d08a8c

services/web/frontend/stylesheets/app/editor/review-panel-new.less

@@ -134,8 +134,8 @@
   }
 
   .review-panel-header {
-    position: fixed;
-    top: var(--review-panel-top);
+    position: sticky;
+    top: 0;
     width: var(--review-panel-width);
     height: @review-panel-header-height;
     display: flex;

services/web/frontend/stylesheets/bootstrap-5/pages/editor/review-panel-new.scss

@@ -145,8 +145,8 @@
   }
 
   .review-panel-header {
-    position: fixed;
-    top: var(--review-panel-top);
+    position: sticky;
+    top: 0;
     width: var(--review-panel-width);
     height: $review-panel-header-height;
     display: flex;