If an encoded SSL CA cert is provided via configuration ensure
it is installed to the system certificate store.
Add focal to list of default images to sync into glance. This
resolved zaza testing failures and ensures that all LTS releases
of Ubuntu are sync'ed by default.
Change-Id: I58f4b89996dc734c4253c2bc2237616434c8143c
Closes-Bug: 1851474
(cherry picked from commit 2dfcecf8d2)