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

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

server/channels/app/remote_cluster.go

@@ -39,6 +39,7 @@ func (a *App) RegisterPluginForSharedChannels(opts model.RegisterPluginOpts) (re
 	rc = &model.RemoteCluster{
 		Name:        opts.Displayname,
 		DisplayName: opts.Displayname,
+		SiteURL:     model.SiteURLPlugin + opts.PluginID, // require a unique siteurl
 		Token:       model.NewId(),
 		CreatorId:   opts.CreatorID,
 		PluginID:    opts.PluginID,