Queens: openstack overcloud generate fencing fails if instackenv.json has pm_type: ilo

[Takashi Kajinami]

Description
===========
Since the following change was merged, TripleO supports pm_type: ilo .
 https://github.com/openstack/tripleo-common/commit/73b6ede2bb706c41c331a4fd95399ca0b1e2047d

However when generating fencing it assumes that pm_type should have '_'
unless it is pxe_ssh, staging-ovirt or ipmi.
 https://github.com/openstack/tripleo-common/blob/stable/queens/tripleo_common/actions/parameters.py#L407

Because of this wrong asusmption in generate fencing, the command fails with "list index out or range"
if the instackenv.json has "pm_type: ilo"

~~~
$ openstack overcloud generate fencing --ipmi-lanplus --ipmi-level administrator --output fencing.yaml ~/instackenv.json
Action tripleo.parameters.generate_fencing execution failed: Failed to run action [action_ex_id=None, action_cls='<class 'mistral.actions.action_factory.GenerateFencingParametersAction'>', attributes='{}', params='{...}']
 list index out of range
~~~

Steps to reproduce
==================
1. Create instackenv.json with pm_type: ilo
2. Run "openstack overcloud generate fencing" with the instackenv.json file

Expected result
===============
The command succeeds without any error

Actual result
=============
The command fails with "list index out of range" error

Environment
===========
The issue is reproduced in Queens.
It seems the issue was fixed by https://github.com/openstack/tripleo-common/commit/812d7e6cbb899983311001d90d6608a0c90f74a5 but this is available only in Rocky and later.

Logs & Configs
==============
N/A

[Takashi Kajinami (kajinamit)]

Marking this as Won't fix because Queens was already EOLed.