removing unecessary css override for the button dropdown caret (#8162)

this css was hiding it, and now it can once again be displayed

src/vendors/theme/assets/styles/components/_dropdowns.scss

@@ -1,24 +1,6 @@
 /* Dropdowns */
 
 .dropdown {
-  .dropdown-toggle {
-    &:after {
-      border-top: 0;
-      border-right: 0;
-      border-left: 0;
-      border-bottom: 0;
-      //font: normal normal normal 24px/1 "Material Design Icons";
-      // content: "\f140";
-      width: auto;
-      height: auto;
-      vertical-align: baseline;
-      font-size: 0.75rem;
-      .rtl & {
-        margin-left: 0;
-        margin-right: 0.255em;
-      }
-    }
-  }
   .dropdown-menu {
     margin-top: 0.75rem;
     font-size: $default-font-size;