Clean unnecessary 'attachToDocument' in 'spec/frontend/monitoring'

Summary

As described in &2419 (closed), we need to clean up our Jest tests from unnecessary attachToDocument usage

Risks

No risks

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