Minor auto-deploy status cleanup

e896641b - Clean up hash returned by environment status

• Removes version, which is now unused.
• Re-uses the revision variable.
• Removes pointless nil || nil fallback.

e39ddc02 - Add a context block about deploys causing inaccuracy

This was suggested by @amyphillips as a basic measure until we can properly resolve gitlab-com/gl-infra/delivery#1537 (closed).