Consider using public mysql rock for testing

Currently tests are using `docker.io/mysql:8.x` in docker compose to execute tests.

We should change it to use our own rock image under `ubuntu/mysql:8.x-24.04_edge`, with the benefits of:
- having pebble UI to mimic managed daemon behavior (e.g. ability to restart)
- "dogfooding" our own products and catching problems early on

Find the Docker Compose configuration that uses docker.io/mysql:8.x and inspect the test service setup. Replace the test image with ubuntu/mysql:8.x-24.04_edge, then run the existing test suite and verify that the tests work with the rock image and its managed-daemon behavior.

Written by the indexing model from the issue text.