Easily copy link to current issue template from URL

What does this MR do and why?

Update URL when setting an issue template, so you can easily copy a link to that kind of issue.

Added some tests to existing feature specs rather than create new fixture and unit test for this file, as it's being replaced by work_item_description_template_listbox.vue.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screen_Recording_2025-01-08_at_15.43.13

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Make a repo with an issue template
2. Go to new issue page
3. Change the template
4. Look at URL
5. Change back to No template
6. Look at URL
7. Have a great day