Remove usage of labels_select_vue in zentao_issues_sidebar_root

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Close this issue

~/vue_shared/components/sidebar/labels_select_vue/labels_select_root.vue is deprecated, and we should remove it from the Zentao Issues sidebar (ee/app/assets/javascripts/integrations/zentao/issues_show/components/sidebar/zentao_issues_sidebar_root.vue).

Because labels on Zentao Issues are read-only, we should be able to render the list of labels using the GlLabel component instead.