[stable/envoy] Fix template for config files (#11180)

- Fix an argument mis-match on applying template for envoy.yaml file

Signed-off-by: Yui Terashima <yui@fog-rock.org>

stable/envoy/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v1
 description: Envoy is an open source edge and service proxy, designed for cloud-native applications.
 name: envoy
-version: 1.4.0
+version: 1.4.1
 appVersion: 1.9.0
 keywords:
 - envoy

stable/envoy/templates/configmap.yaml

@@ -14,5 +14,6 @@ data:
 {{- end -}}
 {{- range $key, $value := .Values.templates }}
   {{ $key }}: |-
-{{ $value | default "" | tpl . | indent 4 }}
+{{ $valueWithDefault := default "" $value -}}
+{{ tpl $valueWithDefault $ | indent 4 }}
 {{- end -}}