[bitnami/mediawiki] Don't create a PVC when using existing claim (#6322)

* Fix creating a PVC when using existing claim

This prevents a new PVC from being created when an existing PVC is
expected.

If an existing claim is used another PVC will get created potentially
causing a default provisioner to act on it but it will never be used.

* [bitnami/mediawiki] bump chart version

bitnami/mediawiki/Chart.yaml

@@ -32,4 +32,4 @@ name: mediawiki
 sources:
   - https://github.com/bitnami/bitnami-docker-mediawiki
   - http://www.mediawiki.org/
-version: 12.2.7
+version: 12.2.8

bitnami/mediawiki/templates/mediawiki-pvc.yaml

@@ -1,4 +1,4 @@
-{{- if .Values.persistence.enabled -}}
+{{- if and .Values.persistence.enabled (not .Values.persistence.existingClaim) -}}
 kind: PersistentVolumeClaim
 apiVersion: v1
 metadata: