[Bug] Notifier alertmanager is not supported

[andrejshapal]

Describe the bug

Contact point failed to be applied for 1 out of 1 instances. Errors:
- monitoring/grafana-risk-and-integrity: creating contact point: [POST /v1/provisioning/contact-points][400] postContactpointsBadRequest {"message":"invalid object specification: failed to validate integration \"Prometheus Alertmanager\" (UID cf1b56c2-8d48-4b4e-a3cc-aa5033910589) of type \"alertmanager\": notifier alertmanager is not supported"}

Version
v5.9.0

To Reproduce
Steps to reproduce the behavior:

apiVersion: grafana.integreatly.org/v1beta1
kind: GrafanaContactPoint
metadata:
  name: prometheus-alertmanager
spec:
  instanceSelector:
    matchLabels:
      instance: grafana-risk-and-integrity
  name: Prometheus Alertmanager
  type: alertmanager
  settings:
    url: http://kube-prometheus-stack-alertmanager.monitoring.svc:9093

Expected behavior
Correct type is: prometheus-alertmanager

Suspect component/Location where the bug might be occurring
This MR: https://github.com/grafana/grafana-operator/pull/1474/files

Grafana 10.4.2