Remove project_key from the JIRA configuration

What does this MR do?

It removes the project key from JIRA configuration.

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

Why was this MR needed?

We used this key in the testing settings but we don't need it for the test. We don't check this key when referencing JIRA issues we also don't check it when posting a comment to JIRA or when we close JIRA issues.

The only useful place where project key is used is when redirecting to the external issue tracker when clicking on issues in menu. This will be removed as part of #33097 (closed)

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
  • 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 #31129 (closed)