GDM 3.34.1: When switch user, greeter session doesn't show on GDM_INITIAL_VT TTY

gdm version: 3.34.1

Greeter session works on wayland.

1. Create multi users
2. Log in to one user
3. Click 'Switch User' button
4. Login dialog screen shows on a free TTY, not GDM_INITIAL_VT(GDM_INITIAL_VT != 1)

If greeter session works on wayland, after system switches to user session, greeter session is killed. After click 'Switch User' button, system switches to greeter session by sending dbus message CreateTransientDisplay to 'org.freedesktop.login1.Manager', not ActivateSessionOnSeat.

In function set_up_for_new_vt system will select a free TTY to show greeter session.

We expect to select GDM_INITIAL_VT TTY to show greeter session.