Use healthchecks on synchronize-secrets

Close: #1273 (closed)
(Bogdan's explanation => #1273 (comment 1922019582))

kubectl get kustomization/synchronize-secrets -o json | jq .spec.healthChecks
[
  {
    "apiVersion": "v1",
    "kind": "Secret",
    "name": "bootstrap-secret",
    "namespace": "cattle-system"
  },
  {
    "apiVersion": "v1",
    "kind": "Secret",
    "name": "cluster-user-auth",
    "namespace": "flux-system"
  },
  {
    "apiVersion": "v1",
    "kind": "Secret",
    "name": "cluster-creator-secret",
    "namespace": "flux-system"
  },
  {
    "apiVersion": "v1",
    "kind": "Secret",
    "name": "keycloak-initial-admin",
    "namespace": "keycloak"
  }
]

kubectl get kustomization/synchronize-secrets -o json | jq .status.conditions
[
  {
    "lastTransitionTime": "2024-05-27T11:58:37Z",
    "message": "Applied revision: sha1:fa8141e25d7e97d96a989cfe4634ca634ac7b0b0",
    "observedGeneration": 2,
    "reason": "ReconciliationSucceeded",
    "status": "True",
    "type": "Ready"
  },
  {
    "lastTransitionTime": "2024-05-27T11:58:37Z",
    "message": "Health check passed in 66.500733ms",
    "observedGeneration": 2,
    "reason": "Succeeded",
    "status": "True",
    "type": "Healthy"
  }
]