test/upgrade: fix tests when netavark uses nftables

Old netavark version only supported iptables, however a new version on
th ehost might use nftables. This breaks the networking tests here as
they are not compatible and you would need to reboot to fix that.

Because this is not possible for our tests make sure we force the
iptables driver always to keep the test working.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

test/upgrade/test-upgrade.bats

@@ -48,6 +48,11 @@ setup() {
     # skip_mount_home=true is required so we can share the storage mounts between host and container,
     # the default c/storage behavior is to make the mount propagation private.
     export _PODMAN_TEST_OPTS="--storage-opt=skip_mount_home=true --cgroup-manager=cgroupfs --root=$PODMAN_UPGRADE_WORKDIR/root --runroot=$PODMAN_UPGRADE_WORKDIR/runroot --tmpdir=$PODMAN_UPGRADE_WORKDIR/tmp"
+
+    # Old netavark used iptables but newer versions might uses nftables.
+    # Networking can only work correctly if both use the same firewall driver so force iptables.
+    printf "[network]\nfirewall_driver=\"iptables\"\n" > $PODMAN_UPGRADE_WORKDIR/containers.conf
+    export CONTAINERS_CONF_OVERRIDE=$PODMAN_UPGRADE_WORKDIR/containers.conf
 }
 
 ###############################################################################
@@ -180,6 +185,7 @@ EOF
             --net=host \
             --cgroupns=host \
             --pid=host \
+            --env CONTAINERS_CONF_OVERRIDE \
             $v_sconf \
             -v /dev/fuse:/dev/fuse \
             -v /run/crun:/run/crun \