Introduce namespace restriction on pod alerts

[t-margheim]

Description

This PR adds a namespace restriction to pod-based alerts in Grafana. Specifically, our default alerts will monitor only Posit Team specific namespaces and monitoring related namespaces. Other namespaces were excluded since pod failures in those namespaces will trigger downstream alerts (if Calico networking fails, the healthcheck alerts will fire). This also means that custom, unrelated pods running in the same workload cluster as a managed PTD deployment will not trigger PTD alerts.

Category of change

• Bug fix (non-breaking change which fixes an issue)
• Version upgrade (upgrading the version of a service or product)
• New feature (non-breaking change which adds functionality)
• Build: a code change that affects the build system or external dependencies
• Performance: a code change that improves performance
• Refactor: a code change that neither fixes a bug nor adds a feature
• Documentation: documentation changes
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

[stevenolen]

lgtm!