[stable/drupal] Refactor StorageClass template to support old Helm versions (#16485)

Signed-off-by: miguelaeh <macabrera@bitnami.com>

stable/drupal/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v1
 name: drupal
-version: 5.1.0
+version: 5.1.1
 appVersion: 8.7.5
 description: One of the most versatile open source content management systems.
 keywords:

stable/drupal/templates/_helpers.tpl

@@ -123,18 +123,33 @@ imagePullSecrets:
 Return  the proper Storage Class
 */}}
 {{- define "drupal.storageClass" -}}
-{{- $storageClass := "" }}
-{{- if .Values.persistence.drupal.storageClass -}}
-    {{- $storageClass = .Values.persistence.drupal.storageClass -}}
-{{- end -}}
+{{/*
+Helm 2.11 supports the assignment of a value to a variable defined in a different scope,
+but Helm 2.9 and 2.10 does not support it, so we need to implement this if-else logic.
+*/}}
 {{- if .Values.global -}}
     {{- if .Values.global.storageClass -}}
-        {{- $storageClass = .Values.global.storageClass -}}
+        {{- if (eq "-" .Values.global.storageClass) -}}
+            {{- printf "\"\"" -}}
+        {{- else }}
+            {{- printf "%s" .Values.global.storageClass -}}
+        {{- end -}}
+    {{- else -}}
+        {{- if .Values.persistence.drupal.storageClass -}}
+              {{- if (eq "-" .Values.persistence.drupal.storageClass) -}}
+                  {{- printf "\"\"" -}}
+              {{- else }}
+                  {{- printf "%s" .Values.persistence.drupal.storageClass -}}
+              {{- end -}}
+        {{- end -}}
+    {{- end -}}
+{{- else -}}
+    {{- if .Values.persistence.drupal.storageClass -}}
+        {{- if (eq "-" .Values.persistence.drupal.storageClass) -}}
+            {{- printf "\"\"" -}}
+        {{- else }}
+            {{- printf "%s" .Values.persistence.drupal.storageClass -}}
+        {{- end -}}
     {{- end -}}
 {{- end -}}
-{{- if (eq "-" $storageClass) -}}
-    {{- printf "\"\"" -}}
-{{- else }}
-    {{- printf "%s" $storageClass -}}
-{{- end -}}
 {{- end -}}