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/remotecluster/invitation.go

@@ -56,7 +56,7 @@ func (rcs *Service) AcceptInvitation(invite *model.RemoteClusterInvite, name str
 	}
 
 	// issue the first ping right away. The goroutine will exit when ping completes or PingTimeout exceeded.
-	go rcs.pingRemote(rcSaved)
+	go rcs.PingNow(rcSaved)
 
 	return rcSaved, nil
 }