* terraform/openstack: Use path.module for ansible_bastion_template.txt
This extends on #7643 by not using path.root, but switching to path.module
to allow use of the terraform code as a module itself. This change then keeps
all calls to the template file stable even for that use-case.
* terraform/openstack: Make sed calls fail on errors
By using a single call with two replacements to use of sed will create proper exit codes
and allowing for errors to be recognized by terraform.
Christian Rohmann