Remove useless attachToDocument usage in ee/spec/frontend

What does this MR do?

As described in &2419 (closed), cleans up our Jest tests from unnecessary attachToDocument usage

Involved specs

• ee/spec/frontend/monitoring/alert_widget_spec.js
• ee/spec/frontend/monitoring/panel_type_spec.js
• ee/spec/frontend/notes/components/note_actions_spec.js
• ee/spec/frontend/operations/components/dashboard/project_header_spec.js
• ee/spec/frontend/packages/details/components/app_spec.js
• ee/spec/frontend/related_items_tree/components/related_items_tree_header_spec.js
• ee/spec/frontend/related_items_tree/components/tree_item_body_spec.js
• ee/spec/frontend/vue_mr_widget/components/approvals/approvals_summary_optional_spec.js

Conformity

• Merge request performance guidelines
• Style guides

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.

Closes: #196754 (closed)