Add delete modal to instance level serverless domain

What does this MR do?

Adds a "delete domain" button and modal to the instance-level serverless domain page.

This is the frontend component of #198445 (closed) (backend implemented in !25841 (merged))

Screenshots

domain has no associations	domain has cluster associations

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

• 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