Resolve "Remove superfluous folders and files"

What does this MR do?

Clean up the repository by deleting unused files and directories.

Further clean up the test/ directory by finally deleting tests that are disabled.

Is there something that needs to be double checked?

No.

Can this MR be accepted?

• Removed unused files/directories
• Deleted unused tests
• [ ] Added/Updated documentation
• Pipeline passing
• Squash option set
• Delete branch option set
• [ ] Added entry to CHANGELOG.md

Assignee: If the Squash option is set, check/update the commit message right before merging!

Related issues

Closes #191 (closed)