Migrate opsuaa deployment from S3 varz to credhub

[ChrisMcGowan]

The current deployment uses variables from S3 varz files that should be moved to credhub to better track expiring certs and reduce exposed secrets in BOSH manifests

Security considerations

By moving from S3 file to credhub, secrets in the BOSH manifest will now be links instead of plain text

Implementation sketch

[links to background notes, sketches, and/or relevant documentation

• Migrate secrets from S3 to credhub
• Update deployment manifest to use credhub links
• Validate with deployment no changes
• Remove S3 file