Convert all uses of `db_config.configuration_hash[*]` to use methods
defined on an implementation of `DatabaseConfigurations::DatabaseConfig`.

Since we want to get away from accessing properties directly on the
underlying configuration hash, we'll move here to accessing those values
via the implementations on `DatabaseConfig` (or more specifically,
`HashConfig`).

There are still codepaths that are passing around `configuration_hash`,
and follow-on PRs will address those with the goal of using
configuration objects everywhere up until the point we pass a resolved
hash over to the underlying client.
Co-authored-by: Neileencodes <eileencodes@gmail.com>