Validate logins consistency in validate_action

According to https://www.erp5.com/erp5-HowTo.Use.And.Define.Workflows/#script-(before)-and-script-(after) the consistency checks should be made in the before script of the user action transition.

This change simply consist in validating in the user action transition, not in the logic transition, for consistency with all other workflows.

/cc @kazuhiko @vpelletier @seb