Migrate allow request access checkbox to gitlab_ui_checkbox_component

app/views/admin/groups/_form.html.haml

-= form_for [:admin, @group] do |f|
+= gitlab_ui_form_for [:admin, @group] do |f|
   = form_errors(@group)
   = render 'shared/group_form', f: f
   = render 'shared/group_form_description', f: f

app/views/shared/_allow_request_access.html.haml

 - label_class = local_assigns.fetch(:bold_label, false) ? 'font-weight-bold' : ''
 
-.gl-form-checkbox.custom-control.custom-checkbox
-  = form.check_box :request_access_enabled, class: 'custom-control-input', data: { qa_selector: 'request_access_checkbox' }
-  = form.label :request_access_enabled, class: 'custom-control-label' do
-    %span{ class: label_class }= _('Allow users to request access (if visibility is public or internal)')
+= form.gitlab_ui_checkbox_component :request_access_enabled,
+    _('Allow users to request access (if visibility is public or internal)'),
+    label_options: { class: label_class },
+    checkbox_options: { data: { qa_selector: 'request_access_checkbox' } }