VED-328: Use SupplierSystem custom attribute. (#547)

Author: mfjarvis

proxies/live/apiproxy/policies/AssignMessage.AddAuthorizationHeaders.xml

@@ -6,7 +6,7 @@
       <Header name="AuthenticationType">{verifyapikey.VerifyAPIKey.CustomAttributes.AuthenticationType}</Header>
       <Header name="Permissions">{verifyapikey.VerifyAPIKey.CustomAttributes.Permissions}</Header>
       <Header name="VaccineTypePermissions">{verifyapikey.VerifyAPIKey.CustomAttributes.VaccineTypePermissions}</Header>
-      <Header name="SupplierSystem">{developer.app.name}</Header>
+      <Header name="SupplierSystem">{verifyapikey.VerifyAPIKey.CustomAttributes.SupplierSystem}</Header>
     </Headers>
   </Set>
   <IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>