Registration service: Health check before continuing deployment

[algattik]

In #178 we disabled the check in the CD pipeline, that the registration service is up and running after Terraform deployment. The reason is that the health check endpoint is not exposed anymore.

We could leave as-is and let the workflow fail when deploying participants.

Or we could set up the check again, e.g.:

• adapt the curl command to succeed if a 401 is returned and fail otherwise
• use the CLI client list participants command with the authority key
• use az container show to check state=running (based on internal health check), waiting if necessary
• use az container exec to run curl within the container, waiting if necessary
• expose port 8181
• use Terratest