Fix translation of title of ZenTao

Use namespace in the translation of the ZenTao title.

Changelog: changed
EE: true

ee/app/views/projects/integrations/zentao/issues/index.html.haml

-- page_title _('ZentaoIntegration|ZenTao issues')
+- page_title s_('ZentaoIntegration|ZenTao issues')
 - add_page_specific_style 'page_bundles/issues_list'
 
 .js-zentao-issues-list{ data: { issues_fetch_path: project_integrations_zentao_issues_path(@project, format: :json),

ee/app/views/projects/integrations/zentao/issues/show.html.haml

-- add_to_breadcrumbs _('ZentaoIntegration|ZenTao issues'), project_integrations_zentao_issues_path(@project)
+- add_to_breadcrumbs s_('ZentaoIntegration|ZenTao issues'), project_integrations_zentao_issues_path(@project)
 - breadcrumb_title zentao_issue_breadcrumb_link(@issue_json)
 - page_title html_escape(@issue_json[:title])