Updates "Nodes are in DRAIN state" failure
What does this MR do?
Updates what to do if the nodes are in DRAIN state
If there's a failure on 'gprd-cny-prepare' due to the nodes being on a DRAIN state, and the release managers don't have access to the nodes, it needs the help of the on-call SRE to fix the problem.
This commit mentions that on the failures document.