Restore alerts in prometheus and dashboards in grafana

[eloiferrer]

Issue description:

• Alerts and dashboards were lost when moving to the new server and have to be added again manually.
• Grafana dashboards were backed up as json, but prometheus needs to be configured before they can be restored.
• Alerts also have to be created again, for the following cases:
  • Portal is down
  • Scholia is down
  • Blazegraph synchronizer is down
  • Back up failed

TODOS:

• Configure prometheus metrics
• Setup alerts
• Restore dashboards from .json files
• Track grafana dashboard and configuration in github (see https://github.com/mpostument/grafana-sync and https://github.com/Beam-Connectivity/grafana-dashboard-manager)
• Remove current dashboard backup script (after implementation of github synchronization)

Acceptance-Criteria

Checklist for this issue:

• Assignee has been set for this issue
• All fields of the issue have been filled
• Issue has been assigned to the main project
• Code was merged
• Feature branch has been deleted and issues were updated / closed
• Issue is tracked by an epic, or the label 'non-epic' is set to the issue.

[LizzAlice]

• Get dashboards running:
  • Backup monitor
  • node exporter
  • traefik
  • traefik 2
  • watchtower
• configure email alerts
  • portal down
  • scholia down
  • blazegraph synchronizer down
  • back up failed