slapos_crm: Reuse Person_hasRequiredRole instead duplicate code.

master/bt5/slapos_crm/SkinTemplateItem/portal_skins/slapos_crm_monitoring/Person_isServiceProvider.py

-if 'service_provider' in context.getRoleList():
-  return True
-
-for assignment in context.contentValues(portal_type="Assignment"):
-  if assignment.getValidationState() == "open" and \
-    assignment.getRole() == 'service_provider':
-    return True
-
-return False
+return context.Person_hasRequiredRole("service_provider")