remove mcrypt

What does this MR do?

This MR removes the mcrypt extension which is deprecated since PHP7.1 and removed in php7.2. This extension is abandonware, the last update to libmcrypt was in 2007. It has been removed from Laravel years ago.

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

No.

Why was this MR needed?

Because it would install irrelevant, obsolete and maybe dangerous php extension.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

None