PLT-6689: fix user image requests (#6946)

* fix user image requests

* fix eslint errors and a few more cache busters

webapp/components/suggestion/at_mention_provider.jsx

@@ -10,7 +10,6 @@ import {autocompleteUsersInChannel} from 'actions/user_actions.jsx';
 
 import AppDispatcher from 'dispatcher/app_dispatcher.jsx';
 import * as Utils from 'utils/utils.jsx';
-import {Client4} from 'mattermost-redux/client';
 import {Constants, ActionTypes} from 'utils/constants.jsx';
 
 import React from 'react';
@@ -66,7 +65,7 @@ class AtMentionSuggestion extends Suggestion {
             icon = (
                 <img
                     className='mention__image'
-                    src={Client4.getUsersRoute() + '/' + user.id + '/image?time=' + user.last_picture_update}
+                    src={Utils.imageURLForUser(user)}
                 />
             );
         }

webapp/components/suggestion/search_user_provider.jsx

@@ -7,7 +7,6 @@ import Provider from './provider.jsx';
 import {autocompleteUsersInTeam} from 'actions/user_actions.jsx';
 
 import AppDispatcher from 'dispatcher/app_dispatcher.jsx';
-import {Client4} from 'mattermost-redux/client';
 import * as Utils from 'utils/utils.jsx';
 import {ActionTypes} from 'utils/constants.jsx';
 
@@ -41,7 +40,7 @@ class SearchUserSuggestion extends Suggestion {
                 <i className='fa fa fa-plus-square'/>
                 <img
                     className='profile-img rounded'
-                    src={Client4.getUsersRoute() + '/' + item.id + '/image?time=' + item.last_picture_update}
+                    src={Utils.imageURLForUser(item)}
                 />
                 <div className='mention--align'>
                     <span>

webapp/components/suggestion/switch_channel_provider.jsx

@@ -58,7 +58,7 @@ class SwitchChannelSuggestion extends Suggestion {
                 <div className='pull-left'>
                     <img
                         className='mention__image'
-                        src={Client4.getUsersRoute() + '/' + channel.id + '/image?time=' + channel.last_picture_update}
+                        src={Utils.imageURLForUser(channel)}
                     />
                 </div>
             );
@@ -239,7 +239,8 @@ export default class SwitchChannelProvider extends Provider {
                     name: user.username,
                     id: user.id,
                     update_at: user.update_at,
-                    type: Constants.DM_CHANNEL
+                    type: Constants.DM_CHANNEL,
+                    last_picture_update: user.last_picture_update || 0
                 },
                 name: user.username
             };