Disable networking-l2gw in scenario004
Disable networking-l2gw in scenario004

Currently, networking-l2gw is broken in master and seems to be mostnly
unmaintained.

Until the situation is clear and the project fixed, this patch is
disabling l2gw from scenario004.

Related-Bug: #1977980
Change-Id: Icd218fee1c47d33a0ef61971ed2a6804b813a05b

openstack/puppet-openstack-integration,openstack/puppet-openstack-integration,openstack/puppet-openstack-integration