gracefully upgrade to new st2-auth secret format

Author: cognifloyd

templates/secrets_st2auth.yaml

@@ -26,7 +26,7 @@ data:
   # Password, used to login to StackStorm system (default: auto-generated)
 {{- $previous := lookup "v1" "Secret" .Release.Namespace $name }}
 {{- if and $previous (not .Values.st2.password) }}
-  ST2_AUTH_PASSWORD: {{ $previous.data.password }}
+  ST2_AUTH_PASSWORD: {{ default $previous.data.password $previous.data.ST2_AUTH_PASSWORD }}
 {{ else }}
   ST2_AUTH_PASSWORD: {{ default (randAlphaNum 12) .Values.st2.password | b64enc | quote }}
 {{ end }}