docs: remove duplicate code for indeterminate (#30471)

site/assets/js/application.js

@@ -19,16 +19,6 @@
     return [].slice.call(list)
   }
 
-  (function () {
-    var checkbox = document.getElementById('flexCheckIndeterminate')
-
-    if (!checkbox) {
-      return
-    }
-
-    checkbox.indeterminate = true
-  })()
-
   makeArray(document.querySelectorAll('.js-sidenav-group'))
     .forEach(function (sidenavGroup) {
       var groupHasLinks = Boolean(sidenavGroup.querySelector('li'))

site/content/docs/4.3/forms/checks.md

@@ -35,7 +35,7 @@ Our checks use custom Bootstrap icons to indicate checked or indeterminate state
 
 Checkboxes can utilize the `:indeterminate` pseudo class when manually set via JavaScript (there is no available HTML attribute for specifying it).
 
-{{< example >}}
+{{< example class="bd-example-indeterminate">}}
 <div class="form-check">
   <input class="form-check-input" type="checkbox" value="" id="flexCheckIndeterminate">
   <label class="form-check-label" for="flexCheckIndeterminate">