payment_mean: don't display specialise as "Mandate"

this is not erp5_accounting data model.
4 jobs for feat/payment_transaction_group_ERPJS in 0 seconds
Status Job ID Name Coverage
  External
passed SlapOS.Eggs.UnitTest-Master.Python2

00:11:11

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:08

passed SlapOS.Eggs.UnitTest-Master.Python2

00:18:18

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:51