dovecot profile: add the attach_disconnected flag

Reported by pfak on IRC

[...] apparmor="DENIED" operation="sendmsg" info="Failed name lookup - disconnected path" error=-13 profile="/usr/sbin/dovecot" name="run/systemd/journal/dev-log" pid=20313 comm="dovecot" requested_mask="w" denied_mask="w" fsuid=0 ouid=0


Acked-by <timeout> for 2.9, 2.10, 2.11 and trunk.