When 'sahara_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: Ie39024c99cad0932f464707adc43019bc1062317
Partial-Bug: 1667789
3603257d29