Check ENV and LABELS by inspect command

[phracek]

Based on the problem with MariaDB 10.11 and ENV and LABELS container variables, I think we can add a test into https://github.com/sclorg/container-ci-suite/blob/main/container_ci_suite/container.py that will check if these variables are present in built image.

The PR with fixed ENV and LABELS variables are here: sclorg/mariadb-container#274

But the PR that introduced the error was: https://github.com/sclorg/mariadb-container/pull/267/files

May be we already have a test but needs to check it.