Alertmanager Backend Down Alert Verbosity

[elipe17]

Description:
Since the introduction of Alertmanager in the deployed environments the dev team and the admin group have been receiving emails about backend services being down when a backend service is being deployed. This is annoying since it is a false positive. To remedy this we should change the tolerance on when to fire these alerts.

Acceptance Criteria:

• Alert is not fired when app is being redeployed
• Alert is still fired when app is actually down
• Testing Checklist has been run and all tests pass
• README is updated, if necessary

Tasks:

• Update the *BackendDown alert definitions in alerts.local.yml and alerts.yml to be more tolerable.
• Test what the minimum tolerance is to keep true alerting as relevant as possible
• Run Testing Checklist and confirm all tests pass