Resolve "Make Twitter Link on Profile page useable by fixing wrong target URL's"

What does this MR do?

It makes wrongly entered Twitter + LinkedIn URL's on User profiles functional by replacing URLs (https://www.linkedin.com/in/ and https://twitter.com/) with empty strings so that they should result in correct usernames.

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

This is my first HAML Code ever so please check if that makes sense and is reasonable.

Why was this MR needed?

Due to no Validation on the Profile Form , there are now wrongly entered URL values.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #31386 (closed)