Default values for secrets in values.yaml is not safe

The way secrets are being handled in this helm chart is not optimal and can lead to security holes. One might decide to provide a values.yaml file during deployment overriding the default keys (like this one: https://github.com/concourse/concourse-chart/blob/master/values.yaml#L1962) but if the chart at some point changes the name of the key, the override will do nothing an the deployment will happen with the default keys, which could be a security problem for public facing instances. No default private key or password should ever be in the default values.yaml file otherwise one would have to go through the whole file before every deployment or upgrade to make sure no default was added that should be overriden.

A better approach would be to run a job that generates all the needed secrets if they are not already there. Let me know what you think.

Start by reviewing the secret defaults in values.yaml, especially around line 1962, and trace how those values are used during chart deployment. Define the required secret-generation and preservation behavior, then verify that deployments and upgrades do not retain insecure default private keys or passwords when overrides are missing.