trigger 'affixed.bs.affix' instead of 'affixed'

Original is triggering `affixed` not `affixed.bs.affix`, only `.on('affixed.bs.affix', ...)` also catch `affixed` event.

Closes #13998.

js/affix.js

@@ -83,7 +83,7 @@
     this.$element
       .removeClass(Affix.RESET)
       .addClass(affixType)
-      .trigger($.Event(affixType.replace('affix', 'affixed')))
+      .trigger($.Event(affixType.replace('affix', 'affixed') + '.bs.affix'))
 
     if (affix == 'bottom') {
       this.$element.offset({