Remove floats from dropdown (#28690)

scss/_dropdown.scss

@@ -20,7 +20,6 @@
   left: 0;
   z-index: $zindex-dropdown;
   display: none; // none by default, but block on "open" of the menu
-  float: left;
   min-width: $dropdown-min-width;
   padding: $dropdown-padding-y 0;
   margin: $dropdown-spacer 0 0; // override default ul

scss/_navbar.scss

@@ -72,7 +72,6 @@
 
   .dropdown-menu {
     position: static;
-    float: none;
   }
 }