Replace the delete SSH confirmation dialog with GlModal

What does this MR do?

This MR replaces the existing browser-default confirmation dialog with a GlModal variant using the brilliant shared modal component: !25471 (merged).

This replacement is specifically for the users sections of the admin area and the users profile.

This also updates the wording of the deletion buttons from "Remove" to "Delete" so it aligns properly with our documentation and the general wording we are using across the product.

Screenshots

Page view

Path	Before	After
[HOST]/admin/users/[USERNAME]/keys
[HOST]/admin/users/[USERNAME]/keys/[ID]
[HOST]/profile/keys
[HOST]/profile/keys/[ID]

Modal view

Path	Before	After
[HOST]/admin/users/[USERNAME]/keys
[HOST]/admin/users/[USERNAME]/keys/[ID]
[HOST]/profile/keys
[HOST]/profile/keys/[ID]

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

Go the paths above and confirm that the modal appears and that you can cancel the action or continue to delete the key and see it is deleted across the product.

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

Related #235945 (closed)