Use recommended instance label for Prometheus/Alertmanager resources

jsonnet/kube-prometheus/components/alertmanager.libsonnet

jsonnet/kube-prometheus/components/prometheus.libsonnet

manifests/alertmanager-alertmanager.yaml

manifests/alertmanager-podDisruptionBudget.yaml

manifests/alertmanager-prometheusRule.yaml

manifests/alertmanager-secret.yaml

manifests/alertmanager-service.yaml

manifests/alertmanager-serviceAccount.yaml

manifests/alertmanager-serviceMonitor.yaml

manifests/prometheus-clusterRole.yaml

manifests/prometheus-clusterRoleBinding.yaml

manifests/prometheus-podDisruptionBudget.yaml

manifests/prometheus-prometheus.yaml

manifests/prometheus-prometheusRule.yaml

manifests/prometheus-roleBindingConfig.yaml

manifests/prometheus-roleBindingSpecificNamespaces.yaml

manifests/prometheus-roleConfig.yaml

manifests/prometheus-roleSpecificNamespaces.yaml

manifests/prometheus-service.yaml

manifests/prometheus-serviceAccount.yaml