Since the new database server outside the Kubernetes cluster, created
for Authelia, was seeded from a backup of the in-cluster server, it
already contained the data from Firefly-III as well. Thus, we can
switch Firefly-III to using it, too.
The documentation for Firefly-III does not mention anything about how
to configure it to use certificate-based authentication for PostgreSQL,
as is required by the new server. Fortunately, it ultimately uses
_libpq_, so the standard `PG...` environment variables work fine. We
just need a certificate issued by the _postgresql-ca_ ClusterIssuer and
the _DCH Root CA_ certificate mounted in the Firefly-III container.