[Issue] host: aks fails on postprovision hook if iac doesn't include aks

[jongio]

I have a two phase provision:

phase 1

1. provision openai
2. run the app locally

phase 2:

1. provision the rest of the services, including aks

when host is aks, azd will do an auto-post-provision hook to do aks deployments or config.

Since phase 1 doesn't have aks provisioned, then this will fail with:

ERROR: deployment failed: failed invoking event handlers for 'postprovision', failed retrieving cluster admin credentials. Ensure your cluster has been configured to support admin credentials, parameter resourceName cannot be empty

I would like the post-provision hook to fail gracefully if the aks resources don't exist.