fix: when collapsing the navbar, do not overlap it with other elements, for example with the tooltip

GitOrigin-RevId: 2db133ce8399c46b620a3a594fc415244c7d9788

services/web/frontend/stylesheets/components/navbar.less

@@ -84,7 +84,7 @@
 }
 
 .navbar-main {
-  z-index: 1;
+  z-index: 9999;
   .container-fluid > .navbar-collapse {
     // High specificity needed to override Bootstrap's default.
     margin: 10px 0 0;