Revert "qemu_passt: Precreate passt logfile"

Revert "qemu_passt: Precreate passt logfile"

This reverts commit 8511b96a319836700b4829816cdae27c3630060d.

Turns out, we need to do a bit more than just plain
qemuSecurityDomainSetPathLabel() which sets svirt_image_t. Passt
has its own SELinux policy and as a part of that they invent
passt_log_t for log files. Right now, I don't know how libvirt
could query that and even if I did, passt SELinux policy would
need to permit relabelling from svirt_t to passt_log_t, which it
doesn't [1].

Until these problems are addressed we shouldn't be pre-creating
the file as it puts users into way worse position - even
scenarios that used to work don't work. But then again - using
log file for passt is usually valuable for developers only and
not regular users.

1: https://bugzilla.redhat.com/show_bug.cgi?id=2209191#c10
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>