PLT-5118 moving to last_picture_update for the profile img (#4985)

webapp/components/user_profile.jsx

@@ -56,7 +56,7 @@ export default class UserProfile extends React.Component {
         let profileImg = '';
         if (this.props.user) {
             name = Utils.displayUsername(this.props.user.id);
-            profileImg = Client.getUsersRoute() + '/' + this.props.user.id + '/image?time=' + this.props.user.update_at;
+            profileImg = Client.getUsersRoute() + '/' + this.props.user.id + '/image?time=' + this.props.user.last_picture_update;
         }
 
         if (this.props.overwriteName) {