Openstack cwd (#7643)

* terraform/openstack: Use path.root for ansible_bastion_template.txt

The path.root variable points to the root module path. Using this
instead of a relative path makes less assumptions about the current
working directory.

* terraform/openstack: Add group_vars_path variable

Previously, the group_vars path was assumed to be in CWD. The
default value for the group_vars_path variable is still relative
to CWD and thus should be backwards compatible if unset.

contrib/terraform/openstack/kubespray.tf

@@ -83,6 +83,7 @@ module "compute" {
   use_server_groups                            = var.use_server_groups
   extra_sec_groups                             = var.extra_sec_groups
   extra_sec_groups_name                        = var.extra_sec_groups_name
+  group_vars_path                              = var.group_vars_path
 
   network_id = module.network.router_id
 }