slapos_erp5: fix consistency message for module `id_generator`

Previous messages were all showing relative URL of the object on which the script was executed.
This was likely a typo in the script and made messages unreadable. This commit restores proper behaviour.
7 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
failed SlapOS-Master.UnitTest-Master

01:48:58

passed SlapOS.Eggs.UnitTest-Master.Python2

00:15:01

failed SlapOS.Eggs.UnitTest-Master.Python3

00:21:47

failed SlapOS.Eggs.UnitTest-Master.Python2

00:15:36

failed SlapOS.Eggs.UnitTest-Master.Python3

00:32:05

failed SlapOS.Eggs.UnitTest-Master.Python3

00:28:10

failed SlapOS.Eggs.UnitTest-Master.Python3

00:17:14