Clean up coffeescript files imported from GitLab CI

What does this MR do?

This MR cleans up CoffeeScript files imported from GitLab CI along with a strategy #19159 (closed). Some files should have been removed in !1987 (merged).

Are there points in the code the reviewer needs to double check?

While I think the Build module should be named as Build, not CiBuild in the JavaScript namespace, please check if it should.

Why was this MR needed?

Removing unused coffeescript files reduces time to build JS and so time to transfer even in production. The fewer files, the better, too.

What are the relevant issue numbers?

Closes #19159 (closed)

Screenshots (if relevant)

n/a

Does this MR meet the acceptance criteria?

• [skipped] CHANGELOG entry added
• [skipped] Documentation created/updated
• [skipped] API support added
• Tests
  • [skipped] Added for this feature/bug
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together