Ping new shared channels remotes immediately (#25850)

* option for auto inviting plugin to all shared channels.

* auto-invite remotes to shared channels when flag set

* fix unit test

* immediately ping new remotes; fix unique siteurl bug

* make i18n-extract

* fix translations

* fix merge conflicts

* make modules-tidy

* revert accidental go.mod change

* revert accidental go.sum changes

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/platform/services/sharedchannel/sync_send_remote.go

@@ -549,7 +549,7 @@ func (scs *Service) sendSyncMsgToRemote(msg *model.SyncMsg, rc *model.RemoteClus
 		return fmt.Errorf("cannot update remote cluster %s for channel id %s; Remote Cluster Service not enabled", rc.Name, msg.ChannelId)
 	}
 
-	if rc.PluginID != "" {
+	if rc.IsPlugin() {
 		return scs.sendSyncMsgToPlugin(msg, rc, f)
 	}