Fix CNI error when net=host is not used in some podman calls

Fix CNI error when net=host is not used in some podman calls

With 'podman version 1.0.0' on RHEL8 beta the 'get ceph version' and
'ceph monitor mkfs' commands fail [1] with "error configuring network
namespace for container Missing CNI default network".

When net=host is added these errors are resolved. net=host is used in
many other calls (grep -R net=host | wc -l --> 38).

Fixes: #3561
Signed-off-by: John Fulton <fulton@redhat.com>
(cherry picked from commit 410abd77455a92a85f0674577e22af0af894964f)