dropdown_list_widget: Show stream icons when widget is disabled.

We show the stream privacy icon for the selected option in
dropdown list widget even if the widget is disabled. It is
fixed by changing the CSS to hide only the "i" element used
for the arrow toggle button and not all the "i" elements in
disabled state.

web/styles/settings.css

@@ -1513,7 +1513,7 @@ $option_title_width: 180px;
             }
         }
 
-        &:disabled i {
+        &:disabled i.fa-chevron-down {
             display: none;
         }
     }