do not set controller ref on psmdb user secret

Signed-off-by: Mayank Shah <mayank.shah@percona.com>

internal/controller/common/helper.go

@@ -262,6 +262,7 @@ func CreateOrUpdateSecretData(
 	database *everestv1alpha1.DatabaseCluster,
 	secretName string,
 	data map[string][]byte,
+	setControllerRef bool,
 ) error {
 	err := UpdateSecretData(ctx, c, database, secretName, data)
 	if err == nil {
@@ -280,10 +281,14 @@ func CreateOrUpdateSecretData(
 		Type: corev1.SecretTypeOpaque,
 		Data: data,
 	}
-	err = controllerutil.SetControllerReference(database, secret, c.Scheme())
-	if err != nil {
-		return err
+
+	if setControllerRef {
+		err = controllerutil.SetControllerReference(database, secret, c.Scheme())
+		if err != nil {
+			return err
+		}
 	}
+
 	// If the secret does not exist, create it
 	return c.Create(ctx, secret)
 }

internal/controller/providers/pg/applier.go

@@ -309,10 +309,16 @@ func (p *applier) applyPMMCfg(monitoring *everestv1alpha1.MonitoringConfig) erro
 		return err
 	}
 
+	// We avoid setting the controller reference for the Secret here.
+	// The PSMDB operator handles Secret cleanup automatically as part of the `delete-psmdb-pvc` finalizer process.
+	// If we were to set the controller reference, the Secret would be deleted before the PSMDB cluster, leading to
+	// the PSMDB operator recreating the Secret and restarting the DB pods to sync updated user information,
+	// which would cause unnecessary restarts.
 	if err := common.CreateOrUpdateSecretData(ctx, c, database, pg.Spec.PMM.Secret,
 		map[string][]byte{
 			"PMM_SERVER_KEY": []byte(apiKey),
 		},
+		true,
 	); err != nil {
 		return err
 	}

internal/controller/providers/psmdb/applier.go

@@ -370,6 +370,7 @@ func (p *applier) applyPMMCfg(monitoring *everestv1alpha1.MonitoringConfig) erro
 		map[string][]byte{
 			"PMM_SERVER_API_KEY": []byte(apiKey),
 		},
+		false,
 	); err != nil {
 		return err
 	}