Replace menu button arrow icon

Although with the previous chevron icon menu button can't be confused with combo box, it looks too cumbersome.

styles/src/components/_menu-button.scss

@@ -23,7 +23,7 @@ $separator-width:    0.75px !default;
     -fx-padding: cfg.$padding-y cfg.$padding-x cfg.$padding-y 0;
 
     >.arrow {
-      @include icons.get("chevron-right", false);
+      @include icons.get("arrow-right", false);
       -fx-background-color: -color-button-fg;
       -fx-min-width: $arrow-button-width;
     }
@@ -34,7 +34,7 @@ $separator-width:    0.75px !default;
   &:openvertically {
     >.arrow-button {
       >.arrow {
-        @include icons.get("expand-more", false);
+        @include icons.get("arrow-drop-down", false);
       }
     }
   }