suricata.yaml: Fix Landlock path settings

suricata.yaml: Fix Landlock path settings

Suricata will complain if it cannot read its own configuration file,
hence read-only access to /etc/suricata must be allowed. Since the list
applies to directories, rather than files, restricting read access to
only /usr/share/misc/magic.mgc is not possible; reading /usr/share/misc
must be allowed instead.

Fixes: #13645
Tested-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>