Changes UI on environment scope on clusters page

What does this MR do?

Modifies clusters form to display a disabled text field for "environment scope." field. This change is needed for https://gitlab.com/gitlab-org/gitlab-ce/issues/52363

EE port: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9171

Screenshots

CE

Before	After

EE

What are the relevant issue numbers?

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/52363

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [-] Documentation created/updated via this MR
• [-] Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• [-] Conforms to the database guides
• [-] Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• [-] Security reports checked/validated by reviewer

Closes #52363 (closed)