Clean up GitHub secrets

[james-garriss]

💡 Summary

In general, there are two related concerns:

• There are potentially some secrets that should be moved from GitHub secrets to Azure Key Vault (AKV).
• There are potentially some secrets in GitHub secrets that should be "backed up" to AKV, as AKV allows us to view the secret.

This is related to the issue that will implement these changes in code: #1505

Motivation and context

We want to use the right tool for the job, taking advatange of the pros of each service.

Implementation notes

• Determine if there are any GitHub secrets that should copied into AKV, not for automation to use but only for backup.
• Move them.
• Look through all GitHub secrets and determine which ones should be put into AKV instead, then move the secrets.
• Move them.

Acceptance criteria

How do we know when this work is done?

• All the secrets are where they are supposed to be.
• All the backup of secrets are where they are supposed to be.