ERP5Security/ERP5GroupManager: don't ignore errors

This plugin already does its own error handling, so we don't really
need to let PAS catch other errors. This way, if an error occurs during
getPortalSecurityCategoryMapping ( which calls ERP5Type_getSecurityCategoryMapping )
we don't have a successful authentication with no groups.
9 jobs for for_testrunner_2 in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-TestRunner2

01:28:29

failed ERP5.UnitTest-TestRunner2

02:43:21

failed ERP5.UnitTest-Zope2-ForTestRunner2

03:58:24

passed ERP5.CodingStyleTest-TestRunner2

01:10:37

passed ERP5.CodingStyleTest-TestRunner2

01:21:23

failed ERP5.UnitTest-TestRunner2

02:18:52

failed ERP5.UnitTest-TestRunner2

03:39:53

failed ERP5.UnitTest-Zope2-ForTestRunner2

02:32:12

failed ERP5.UnitTest-Zope2-ForTestRunner2

03:40:19