PLT-3960 Don't show (message deleted) placeholder to the user that deleted the message (#4839)

* on post delete remove the whole post for the owner of the post while other user will still see post deleted message

* now the deleter wont see the post while the other users will see deleted message

* removed fromSocket check and now calling PostStore.removePost instead of PostStore.deletePost from view

* fixed the bug which was causing to show message deleted until next action

* added remove post from store to global action

* moved removePostFromStore from global actions to post actions

webapp/actions/post_actions.jsx

@@ -362,3 +362,8 @@ export function createPost(post, doLoadPost, success, error) {
         }
     );
 }
+
+export function removePostFromStore(post) {
+    PostStore.removePost(post);
+    PostStore.emitChange();
+}

webapp/components/delete_post_modal.jsx

@@ -9,6 +9,7 @@ import ModalStore from 'stores/modal_store.jsx';
 import {Modal} from 'react-bootstrap';
 import * as AsyncClient from 'utils/async_client.jsx';
 import AppDispatcher from '../dispatcher/app_dispatcher.jsx';
+import {removePostFromStore} from 'actions/post_actions.jsx';
 import Constants from 'utils/constants.jsx';
 
 import {FormattedMessage} from 'react-intl';
@@ -54,8 +55,7 @@ export default class DeletePostModal extends React.Component {
             this.state.post.channel_id,
             this.state.post.id,
             () => {
-                PostStore.deletePost(this.state.post);
+                removePostFromStore(this.state.post);
-
                 if (this.state.post.id === PostStore.getSelectedPostId()) {
                     AppDispatcher.handleServerAction({
                         type: ActionTypes.RECEIVED_POST_SELECTED,