erp5_web_project_ui_test: update test

bt5/erp5_web_project_ui_test/SkinTemplateItem/portal_skins/erp5_web_project_test/ERP5Site_createTestStartedProject.py

 portal = context.getPortalObject()
 project_reference = 'test-project'
-publication_section = context.restrictedTraverse('portal_categories/publication_section/project_home_page_for_test')
 
 module = portal.getDefaultModule('Project')
 project = module.newContent(portal_type = 'Project',
@@ -8,6 +7,9 @@ project = module.newContent(portal_type = 'Project',
 project.validate()
 
 if home_page:
+  system_preference = portal.portal_preferences.getActiveSystemPreference()
+  system_preference.setPreferredPublicationSection("project_home_page_for_test")
+  publication_section = context.restrictedTraverse('portal_categories/publication_section/project_home_page_for_test')
   module = portal.getDefaultModule('Web Page')
   home_page = module.newContent(portal_type = 'Web Page',
                                 reference = project_reference + '-home.page',