Set delete group runner modal's button variant

Sets the delete group runner modal's button variant to danger instead of
the default confirm.

app/views/groups/runners/_runner.html.haml

@@ -76,5 +76,5 @@
             = sprite_icon('close', css_class: 'gl-icon')
       - else
         .btn-group
-          = link_to group_runner_path(@group, runner), method: :delete, class: 'gl-button btn btn-danger btn-icon has-tooltip', title: _('Remove'), ref: 'tooltip', aria: { label: _('Remove') }, data: { placement: 'top', container: 'body', confirm: _('Are you sure?') } do
+          = link_to group_runner_path(@group, runner), method: :delete, class: 'gl-button btn btn-danger btn-icon has-tooltip', title: _('Remove'), ref: 'tooltip', aria: { label: _('Remove') }, data: { placement: 'top', container: 'body', confirm: _('Are you sure?'), confirm_btn_variant: "danger" } do
             = sprite_icon('close', css_class: 'gl-icon')