Configure (upcoming) Patroni bootstrap labels feature (#2872)

Set the value from the critical-operation-pdb's selector if PDBs are enabled

pkg/cluster/k8sres.go

@@ -1010,6 +1010,9 @@ func (c *Cluster) generateSpiloPodEnvVars(
 
 	if c.patroniUsesKubernetes() {
 		envVars = append(envVars, v1.EnvVar{Name: "DCS_ENABLE_KUBERNETES_API", Value: "true"})
+		if c.OpConfig.EnablePodDisruptionBudget != nil && !(*c.OpConfig.EnablePodDisruptionBudget) {
+			envVars = append(envVars, v1.EnvVar{Name: "KUBERNETES_BOOTSTRAP_LABELS", Value: "{\"critical-operation\":\"true\"}"})
+		}
 	} else {
 		envVars = append(envVars, v1.EnvVar{Name: "ETCD_HOST", Value: c.OpConfig.EtcdHost})
 	}