Allow drop slots when it gets deleted from the manifest (#2089)

* Allow drop slots when it gets deleted from the manifest
* use leader instead replica to query slots
* fix and extend unit tests for config update checks

Co-authored-by: Felix Kunde <felix-kunde@gmx.de>

pkg/cluster/cluster.go

@@ -84,6 +84,7 @@ type Cluster struct {
 	userSyncStrategy spec.UserSyncer
 	deleteOptions    metav1.DeleteOptions
 	podEventsQueue   *cache.FIFO
+	replicationSlots map[string]interface{}
 
 	teamsAPIClient      teams.Interface
 	oauthTokenGetter    OAuthTokenGetter
@@ -140,6 +141,7 @@ func New(cfg Config, kubeClient k8sutil.KubernetesClient, pgSpec acidv1.Postgres
 		podEventsQueue:      podEventsQueue,
 		KubeClient:          kubeClient,
 		currentMajorVersion: 0,
+		replicationSlots:    make(map[string]interface{}),
 	}
 	cluster.logger = logger.WithField("pkg", "cluster").WithField("cluster-name", cluster.clusterName())
 	cluster.teamsAPIClient = teams.NewTeamsAPI(cfg.OpConfig.TeamsAPIUrl, logger)
@@ -374,6 +376,10 @@ func (c *Cluster) Create() error {
 		}
 	}
 
+	for slotName, desiredSlot := range c.Spec.Patroni.Slots {
+		c.replicationSlots[slotName] = desiredSlot
+	}
+
 	return nil
 }