Fix tenant column on pre_prov partial

In cases where both amazon and openstack images are available in the "Select and
Image" table in the _pre_prov partial, the table shows up with uneven rows.
This is caused by amazon not having tenants whereas openstack does have tenants.

Originally, the logic for showing the table column header would arbitrarily
include the header based solely on the first template in the list to be shown.
Now, the column header is shown if any of the templates in the list can show a
cloud tenant.

Also, the logic for showing the table cell is based on whether the table tenants
header is shown.

Additionally, the logic for showing the data inside the table cell is based on
whether the template in the current column can respond_to the `cloud_tenant`
method.

https://bugzilla.redhat.com/show_bug.cgi?id=1127459