When 'octavia_galera_use_ssl' is True, use an encrypted connection to
the database using either a self-signed or user-provided CA certificate.
A new non-voting test has been added to verify that the role remains
functional when enabling SSL features.
Change-Id: I7a43d313474e17d7e968a5a9510368e3abdf6682
Partial-Bug: 1667789
8cc05a3d00