Improve perf for channel switching, fix team switching issues (#6286)

* Improve perf for channel switching, fix team switching issues

* Fix last channel when switching teams

webapp/actions/post_actions.jsx

@@ -25,7 +25,7 @@ import store from 'stores/redux_store.jsx';
 const dispatch = store.dispatch;
 const getState = store.getState;
 import {getProfilesByIds} from 'mattermost-redux/actions/users';
-import {getChannelMember} from 'mattermost-redux/actions/channels';
+import {getMyChannelMember} from 'mattermost-redux/actions/channels';
 
 export function handleNewPost(post, msg) {
     let websocketMessageProps = {};
@@ -41,7 +41,7 @@ export function handleNewPost(post, msg) {
             Client.setTeamId(msg.data.team_id);
         }
 
-        getChannelMember(post.channel_id, UserStore.getCurrentId())(dispatch, getState).then(() => completePostReceive(post, websocketMessageProps));
+        getMyChannelMember(post.channel_id)(dispatch, getState).then(() => completePostReceive(post, websocketMessageProps));
     }
 
     if (msg && msg.data) {