Revert "heat: ensure admin has heat_stack_owner role"

This can prevent spinal-stack from being deployed with the following message

```
Error: Could not retrieve catalog from remote server: Error 400 on SERVER: Duplicate declaration: Keystone_user_role[admin@admin] is already declared in file /etc/puppet/modules/keystone/manifests/roles/admin.pp:66; cannot rede
clare at /etc/puppet/modules/cloud/manifests/orchestration/engine.pp:44 on node openstack1
```

This is due to the fact that in `roles/admin.pp` we have (https://github.com/stackforge/puppet-keystone/blob/master/manifests/roles/admin.pp#L72-L74)

```
    keystone_user_role { "${admin}@${admin_tenant}":
      ensure => present,
      roles  => 'admin',
    }
```

The proper way to do it would be to pass an array to roles, and includes `heat_stack_owner` next to `admin`.  `keystone_user_role` handles already arrays, a slight modification needs to be done in the keystone puppet module. https://review.openstack.org/#/c/132350/


This reverts commit a6416cc98563f016f17302c52361a3e40ff19812.