Fix ceph iscsi gw not working on ubuntu focal
Fix ceph iscsi gw not working on ubuntu focal

Limit ceph iscsi ubuntu support only to Focal. As only Focal has the
required packages and we don't want to install ceph-iscsi from master
source code which is changing all the way is not a good way for CI.

Remove api_host setting, let it be ceph iscsi default setting "::"[1],
Which references to ceph-ansible configuration[2]. This makes
rbd-target-api accessible for both localhost(gwcli) and HOST_IP.
Otherwise iscsi gateway creation will fail in newer version
ceph-iscsi[3].

Change minimum-gateways default to 1 for newer version ceph-iscsi,
otherwise client creation will fail on all-in-one setup[4].

Fix gateway creation failure with error:
"The first gateway defined must be the local machine"
Ceph-iscsi requires gateway name to be FQDN, sometimes hostname is not
the same as FQDN.

Fix stop_ceph_iscsi run twice.

Remove setup_packages_for_iscsi as openstack won't support projects that
require packages installed with git clone.

[1]: https://github.com/ceph/ceph-iscsi/blob/master/ceph_iscsi_config/gateway_setting.py#L174
[2]: https://github.com/ceph/ceph-ansible/blob/master/roles/ceph-iscsi-gw/templates/iscsi-gateway.cfg.j2
[3]: https://github.com/ceph/ceph-iscsi/issues/193
[4]: https://github.com/ceph/ceph-iscsi/issues/195

Change-Id: I215b870c66cc27f10f8a6bf18d93feda477a3970

openstack/devstack-plugin-ceph