Remove btn-group style from users' list

We don't group these buttons in other lists (eg. payments, subscription
types, segments, lists on user's detail page). It looks out of place when
switching between them.

remp/crm#2398, remp/crm#2487

src/templates/UsersAdmin/default.latte

@@ -85,7 +85,7 @@
               </span>
             </td>
             <td style="min-width: 120px;">
-              <div class="btn-group btn-group dropup">
+              <div>
                 <a n:href="show $u->id" class="btn btn-sm btn-info" role="button" title="{_users.admin.actions.show}"><i class="fa fa-eye"></i> </a>
                 <a n:href="edit $u->id" class="btn btn-sm btn-primary" role="button" title="{_users.admin.actions.edit}"><i class="fa fa-edit"></i> </a>
                 {if $u->active}