Remove useless attachToDocument usage in spec/frontend/monitoring

What does this MR do?

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

Involved specs

• spec/frontend/monitoring/components/charts/time_series_spec.js
• spec/frontend/monitoring/components/dashboard_spec.js
• spec/frontend/monitoring/components/dashboard_time_url_spec.js
• spec/frontend/monitoring/components/dashboard_time_window_spec.js
• spec/frontend/monitoring/panel_type_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: #196758 (closed)