slapos_erp5: Call other Constraint Script due precedence

   Since the ID is used, it is important to "enableGlobal" before set conversion server configuration.

master/bt5/slapos_erp5/SkinTemplateItem/portal_skins/slapos_erp5/SystemPreference_checkConversionServerConsistency.py

-if context.getPortalType() not in [ "System Preference"]:
+error_log = []
+
+if context.getPortalType() not in ["System Preference"]:
   return []
 
+if context.getId() == "slapos_default_system_preference" and context.getPreferenceState() != "global":
+  error_log.extend(context.SystemPreference_checkSystemPreferenceConsistency(fixit=fixit, **kw))
+
 if context.getPreferenceState() != "global":
   return []
 
@@ -14,7 +19,8 @@ if expected_url != url:
   if fixit:
     system_preference.setPreferredDocumentConversionServerUrl(expected_url)
     fixing = ' (fixed)'
-  return ["Conversion Server not configured as expected%s: %s" %
-    (fixing, "Expect %s\nGot %s" % (expected_url, url))]
-else:
-  return []
+  
+  error_log.append("Conversion Server not configured as expected%s: %s" %
+    (fixing, "Expect %s\nGot %s" % (expected_url, url)))
+
+return error_log