Migrate import group to shared alert HAML

app/views/groups/_import_group_from_another_instance_panel.html.haml

@@ -4,8 +4,9 @@
       %h4.gl-display-flex
         = s_('GroupsNew|Import groups from another instance of GitLab')
       = link_to _('History'), history_import_bulk_imports_path, class: 'gl-link gl-ml-auto'
-    .gl-alert.gl-alert-warning{ role: 'alert' }
-      = sprite_icon('warning', css_class: 'gl-icon s16 gl-alert-icon gl-alert-icon-no-title')
+    = render 'shared/global_alert',
+      dismissible: false,
+      variant: :warning do
       .gl-alert-body
         - docs_link_start = '<a href="%{url}" target="_blank" rel="noopener noreferrer">'.html_safe % { url: help_page_path('user/group/import/index.md') }
         - docs_link_end = '</a>'.html_safe