+++ This bug was initially created as a clone of Bug #1692823 +++
Description of problem:
=======================
A recent change[1] to Octavia added a parameter named server_certs_key_passphrase, which means that we should generate a password for it to avoid using the default value.
OctaviaServerCertsKeyPassphrase should be added to the list of generated password/secrets.
[1] https://review.openstack.org/#/q/I06d329ca53bc36bd27f7870ae7c7ca0cf18575b2