Clean Stanza Create pgtask & Job After Init

When a PostgreSQL cluster is initialized for the first time, the stanza
create pgtask and the Kubernetes Job associated with it are now
automatically deleted.  This ensures that subsequent update events in
the Job controller for a stanza-create Job do not trigger additional
"initial backups" Jobs for the cluster.

Issue: [ch10277]
Issue: #2106

Author: andrewlecuyer

internal/controller/job/backresthandler.go

@@ -229,6 +229,14 @@ func (c *Controller) handleBackrestStanzaCreateUpdate(job *apiv1.Job) error {
 		backrestoperator.CreateInitialBackup(c.Client, job.ObjectMeta.Namespace,
 			clusterName, backrestRepoPodName)
 
+		// now that the initial backup has been initiated, proceed with deleting the stanza-create
+		// pgtask and associated Job.  This will ensure any subsequent updates to the stanza-create
+		// Job do not trigger more initial backup Jobs.
+		if err := backrest.CleanStanzaCreateResources(namespace, clusterName, c.Client); err != nil {
+			log.Error(err)
+			return err
+		}
+
 	}
 	return nil
 }