This commit refactors the environment variable definitions
in the `common.yaml` template for the Paperless-ngx chart.
The structure has been simplified by removing the unnecessary
nested "controllers: main: type: deployment" section, directly
defining the `env` block. This improves readability and
maintainability of the Helm template.
No functional changes were introduced, and existing behaviors
are preserved. The refactor aims to streamline the configuration
management process for better clarity when setting up
environment variables related to services like PostgreSQL,
MariaDB, and Redis.