Comment 9 for bug 1915512

I just removed the following the flag unit.departed then update_controller_ip_port_list can be triggered after removing unit.

reactive.flags.register_trigger(
    when_not='cluster.connected', set_flag='unit.departed')

@reactive.when('unit.departed')
def update_controller_ip_port_list():

This is self-test data for patchset5 - https://paste.ubuntu.com/p/rkJW5NKcKY/