Remove Command Line section from Rails cheat sheet

What does this MR do and why?

Closes #367363 (closed)

This MR removes the Command Line section from the rails cheat sheet. There are currently 3 subsections that already exist elsewhere in the documentation:

• Check the GitLab version fast - this is similarly already covered in this documentation
• Debugging SSH - already covered in this documentation
• Debugging over HTTPS - covered in the same documentation linked above

As a result, the entire section can be removed.

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