Add `$CI_ENVIRONMENT_URL` as a job variable

What does this MR do?

Add $CI_ENVIRONMENT_URL as a job variable

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

I also changed += to Array#concat to reduce temporary arrays.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests
  • Added for this feature/bug

What are the relevant issue numbers?

Closes #25680 (closed)