Metrics: Delete UI for Grafana authentication
As part of #346541 (closed) remove Grafana authentication
section in Settings > Monitor
Relevant files
- app/assets/javascripts/grafana_integration
- spec/frontend/grafana_integration
- doc/operations/metrics/embed_grafana.md
Implementation plan
- delete
Grafana authentication
section inSettings > Monitor
- delete relevant docs
Verification steps
These areas of the app should remain unavailable & without regressions to other features: