Add explicit schema version check

What does this MR do?

Add an explicit schema version check to an initializer. It is making assumptions about the state of the database by checking individual tables. This is rather brittle, e.g. when testing migration paths (starting from an old database schema version).

See #207458 (closed).

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content