MM-14532 Send "clear" notification to every other session (#10459)

app/plugin_api.go

@@ -376,7 +376,7 @@ func (api *PluginAPI) AddChannelMember(channelId, userId string) (*model.Channel
 		return nil, err
 	}
 
-	return api.app.AddChannelMember(userId, channel, userRequestorId, postRootId, false)
+	return api.app.AddChannelMember(userId, channel, userRequestorId, postRootId, "")
 }
 
 func (api *PluginAPI) GetChannelMember(channelId, userId string) (*model.ChannelMember, *model.AppError) {