Remove duplicate CSS selector in classic theme

Closes #5100

src/scss/theme/classic/_multiple.scss

@@ -56,9 +56,6 @@
   .select2-selection--multiple {
     .select2-selection__choice {
       float: right;
-    }
-
-    .select2-selection__choice {
       margin-left: 5px;
       margin-right: auto;
     }