refactor(markdown): Migrated tests to Jest

What does this MR do?

Migrates the markdown spec files from Karma to Jest

Fixes #58828 (moved)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content