run: when disconnected from PTY forwarder, exit event loop if not --wait

run: when disconnected from PTY forwarder, exit event loop if not --wait

Follow-up for ade0789fabbf01b95bf54d32f8cab1217a753f03

The change in behavior was partly intentional, as I think
if both --wait and --pty are used, manually disconnecting
from PTY forwarder should not result in systemd-run exiting
with "Finished with ..." log. But we should check for
--wait here.

Closes #32953