fix: remove defunct reliability teams
Reliability teams have moved to squads: https://about.gitlab.com/handbook/engineering/infrastructure/team/reliability/
The old teams -- CoreInfra, Datastores and Observability are now defunct.
This MR removes the references from the metric-catalog and the service-catalog to those teams.
Required for !4079 (merged) and #70 (closed).
Edited by Andrew Newdigate