Description of problem:

The option to scale infra provider is not available
The GUI shows 5 nodes without the option to select additional node to scale with it.

Version-Release number of selected component (if applicable):

5.4.5.2

How reproducible:
100%

Steps to Reproduce:
1. login to CFME
2. select infrastructure provider
3. click on the infra provider thumbnail
4. configuration -> scale this infra...

Actual results:

UI show 5 nodes the options to scale out are not available 

Expected results:

Scale option should allow to scale with the available host 

Additional info:

in openstack undercloud 4 used nodes

[stack@instack ~]$ nova list
+--------------------------------------+-------------------------+--------+------------+-------------+---------------------+
| ID                                   | Name                    | Status | Task State | Power State | Networks            |
+--------------------------------------+-------------------------+--------+------------+-------------+---------------------+
| 76dfc7e7-21ae-4aa8-905c-c65e14419e15 | overcloud-controller-0  | ACTIVE | -          | Running     | ctlplane=192.0.2.10 |
| d4e7adf6-c764-455f-8b78-077923eea648 | overcloud-controller-1  | ACTIVE | -          | Running     | ctlplane=192.0.2.7  |
| 5e2274b5-1c47-45f5-a719-5c25ebdf91a8 | overcloud-controller-2  | ACTIVE | -          | Running     | ctlplane=192.0.2.9  |
| 160e8577-a6ad-48f7-a5d2-cb854478b700 | overcloud-novacompute-0 | ACTIVE | -          | Running     | ctlplane=192.0.2.8  |
+--------------------------------------+-------------------------+--------+------------+-------------+---------------------+

5 available nodes


+--------------------------------------+------+--------------------------------------+-------------+--------------------+-------------+
| UUID                                 | Name | Instance UUID                        | Power State | Provisioning State | Maintenance |
+--------------------------------------+------+--------------------------------------+-------------+--------------------+-------------+
| 28e5d7df-6fa0-4d69-b4f4-868636e16b8f | None | d4e7adf6-c764-455f-8b78-077923eea648 | power on    | active             | False       |
| 8e1f729e-b4fe-4e32-a05b-aeef85449d2a | None | None                                 | power off   | available          | False       |
| 8dd94da1-bc33-4eca-af46-16c22782c43b | None | 5e2274b5-1c47-45f5-a719-5c25ebdf91a8 | power on    | active             | False       |
| dd8f0356-5da6-4187-8efb-5a26e01ce846 | None | 160e8577-a6ad-48f7-a5d2-cb854478b700 | power on    | active             | False       |
| 78259be7-4c09-4789-be28-c9c57fc04f88 | None | 76dfc7e7-21ae-4aa8-905c-c65e14419e15 | power on    | active             | False       |
+--------------------------------------+------+--------------------------------------+-------------+--------------------+-------------+