feat: add observability (Prometheus) to local-setup

[crstrn13]

Problem

Currently, make local-setup does not configure observability/metrics for the local Kuadrant environment:

• Prometheus is not deployed
• Kuadrant CR does not have observability enabled
• Developers cannot access metrics locally for debugging
• Local development doesn't match production observability setup

Proposed Solution

1. Deploy Prometheus Operator

Deploy Prometheus Operator in its designated namespace for metrics collection and monitoring.

2. Configure Kuadrant CR Observability

Update Kuadrant CR to enable observability:

apiVersion: kuadrant.io/v1beta1
kind: Kuadrant
metadata:
  name: kuadrant
spec:
  observability:
    enabled: true

Benefits

• ✅ Developers can debug with metrics locally
• ✅ Local environment matches production observability setup
• ✅ Enables running observability-related tests locally

Acceptance Criteria

• make local-setup deploys Prometheus Operator
• Kuadrant CR has observability.enabled: true
• Metrics are accessible via Prometheus UI
• Observability tests pass on local-setup: make testsuite/tests/singlecluster/observability/
• Documentation updated with observability setup instructions

Related

• Observability tests: testsuite/tests/singlecluster/observability/