There are cases when a multinode deployment ends up in unusable
keystone public wsgi on some nodes.
The root cause is that keystone public wsgi doesn't find fernet
keys on startup - and then persists on sending 500 errors to any
requests - due to a race condition between
fernet_setup/fernet-push.sh and keystone startup.
Depends-On: https://review.opendev.org/703742/
Change-Id: I63709c2e3f6a893db82a05640da78f492bf8440f
Closes-Bug: #1846789
0799782ce8