Refactor InstallerNonDefaultDatabaseDriverTest to avoid DatabaseDriverUninstallValidator re-fetch the database connection

Problem/Motivation

In order to allow InstallerNonDefaultDatabaseDriverTest execute, DatabaseDriverUninstallValidator::validate() needs to get a new connection set by the test than the one passed in construction.

We should not have to alter runtime execution paths to fulfill test requirements.

Proposed resolution

Refactor InstallerNonDefaultDatabaseDriverTest so that the injected connection be used. TBD how.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet