Bug 1679521

Description of problem:
The expected way of preparing metrics installation is described here: https://gerrit.ovirt.org/#/c/97643/48/roles/oVirt.metrics-store-installation/README.md 
User is supposed to copy /etc/ovirt-engine-metrics/config.yml.example and customize the default values for the variables. It works fine for most of the variables, but there is one potential problem. Let me describe the scenario:
- User specifies this: openshift_ovirt_storage_domain_name: my_nfs_0
- Then they run ovirt-metrics-store-installation.yml playbook
- During this playbook, OS image specified in qcow_url is downloaded
- That image is then uploaded to RHV engine with name "rhelguest76" unless overridden by the user
- During the upload, the role oVirt.image-template needs to determine storage domain for the disk of the template 
- The way this storage domain is determined can be seen here: https://github.com/oVirt/ovirt-ansible-image-template/blob/43b04c27d001f98655d97b8e4553d6797a251d4f/tasks/qcow2_image.yml#L67
- It basically looks at all the data domains in your Data Center and takes the first one
- Here comes the problem! Let's say the first data domain it finds is "hosted_storage". It might very well happen in hosted engine environment
- Disk for your template is thus placed into hosted_storage data domain and the ovirt-metrics-store-installation.yml finishes successfully
- Then you start install_okd.yml playbook. During its execution, it tries to create OKD all-in-one node from previously created template
- HOWEVER, your template's disk is located on hosted_stored while we specified openshift_ovirt_storage_domain_name: my_nfs_0. Here's where the playbook fails - because we cannot create a new VM disk on different storage domain.


Version-Release number of selected component (if applicable):
ovirt-engine-metrics-1.2.1-0.0.master.20190220121053.el7.noarch (patchset 48)

How reproducible:
Depends on environment

Steps to Reproduce:
Basically the description

Actual results:
- install_okd.yml might fail because of this

Expected results:
- The template created in bastion creation phase should be in the same data domain that is specified in openshift_ovirt_storage_domain_name variable.

Additional info:
Two workarounds exist: 
1) After the bastion creation, you can manually copy your template's disk to the correct storage domain
2) You can specify this in your config.yml:
template_disk_storage: my_nfs_0
There's basically nothing wrong with the second option. The problem is that it's definitely not obvious to the user that such an option can be used though. It's not specified neither in README nor in example config. But that's probably okay. There's not really a new for another variable in config as long as we make sure that the template is created in the same storage domain as specified in openshift_ovirt_storage_domain_name variable.