Remove duplicate content property

Not sure how that happened originally 🤷‍♂️

Author: dancormier

lib/components/button-group/button-group.less

@@ -58,7 +58,6 @@
         & .s-btn--text {
             &:before {
                 content: attr(data-text);
-                content: attr(data-text) / "";
                 font-weight: bold;
                 height: 0;
                 pointer-events: none;

lib/components/navigation/navigation.less

@@ -119,7 +119,6 @@
     & &--item-text {
         &:before {
             content: attr(data-text);
-            content: attr(data-text) / "";
             font-weight: bold;
             height: 0;
             pointer-events: none;