Automate nightly deployment of a test instance

### Description / Background

It would be useful if we could automatically deploy an instance based on the latest snapshot version each night, so that we have an instance already deployed for manual testing. We could include the standalone system test infrastructure as part of this, so we can generate data when needed. This could also provide some coverage of the upgrade process.

### Technical Notes / Implementation Details

We'll need to do this in a separate repository in order to have access to deploy an instance.

No files, tests, or entry points are named; start by reviewing the separate-repository requirement, latest snapshot version, and standalone system test infrastructure described in the issue. Done means a test instance is deployed nightly, supports manual data generation, and provides some upgrade-process coverage.

Written by the indexing model from the issue text.