use bitnami charts as dependencies

### Suggestion for improvement and simplification

Instead of defining MySQL and Redis "charts" as subcharts just use existing charts from Bitnami:
- https://artifacthub.io/packages/helm/bitnami/mysql
- https://artifacthub.io/packages/helm/bitnami/redis

Start by inspecting the repository's chart and dependency definitions, then compare them with the Bitnami MySQL and Redis charts linked in the issue. Render or lint the chart to verify that the existing services still work through those dependencies; done means the local subcharts are replaced without breaking chart behavior.

Written by the indexing model from the issue text.