managed: make it harder to make mistakes in upgrade process
Created by: bobheadxi
I just did a customer upgrade (https://github.com/sourcegraph/deploy-sourcegraph-managed/pull/10) and the scariest part was probably making sure I was running commands on the right thing. This change makes it easier to set up variables to correctly substitute in the correct values - CUSTOMER
, DEPLOYMENT
, etc.
Also makes misc. improvements based on doing this