Refactor delete group button: rename adjourned to delayed in code

What does this MR do and why?

Related to #339478

During the implementation of delayed group and project deletion, we used various terminology in the documentation and in the codebase. We converged on a single set of terms. We use:

• delayed instead of adjourned or soft-deleted: #223013 (closed)
• delete instead of remove: #221100 (closed)

This MR focuses on "group deletion button" by renaming ee/app/views/groups/settings/_adjourned_deletion.html.haml to ee/app/views/groups/settings/_delayed_deletion.html.haml

Screenshots or screen recordings

No visible changes

How to set up and validate locally

To delete a group:

1. On the top bar, select Main menu > Groups and find your group.
2. On the left sidebar, select Settings > General.
3. Expand the Advanced section.
4. In the Remove group section, select Remove group.
5. Type the group name.
6. Select Confirm.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #339478