Migrate checkboxes to Pajamas form

Remove unneeded helper

app/helpers/projects_helper.rb

@@ -650,14 +650,6 @@ module ProjectsHelper
     "You must enable HTTPS for all your domains first"
   end
 
-  def pages_https_only_label_class
-    if pages_https_only_disabled?
-      "list-label disabled"
-    else
-      "list-label"
-    end
-  end
-
   def filter_starrer_path(options = {})
     options = params.slice(:sort).merge(options).permit!
     "#{request.path}?#{options.to_param}"

app/views/projects/pages/_pages_settings.html.haml

@@ -2,20 +2,19 @@
 - can_enforce_https_only=Gitlab.config.pages.external_http || Gitlab.config.pages.external_https
 
 - return unless can_edit_max_page_size || can_enforce_https_only
-= form_for @project, url: project_pages_path(@project), html: { class: 'inline', title: pages_https_only_title } do |f|
+= gitlab_ui_form_for @project, url: project_pages_path(@project), html: { class: 'inline', title: pages_https_only_title } do |f|
   - if can_edit_max_page_size
     = render_if_exists 'shared/pages/max_pages_size_input', form: f
 
   - if can_enforce_https_only
     .form-group
-      .form-check
-        = f.check_box :pages_https_only, class: 'form-check-input', disabled: pages_https_only_disabled?
-        = f.label :pages_https_only, class: pages_https_only_label_class do
-          %strong
-            = s_('GitLabPages|Force HTTPS (requires valid certificates)')
+      = f.gitlab_ui_checkbox_component :pages_https_only,
+        s_('GitLabPages|Force HTTPS (requires valid certificates)'),
+        checkbox_options: { disabled: pages_https_only_disabled? },
+        label_options: { class: 'label-bold' }
       - docs_link_start = "<a href='#{help_page_path('user/project/pages/custom_domains_ssl_tls_certification/index', anchor: 'force-https-for-gitlab-pages-websites')}' target='_blank' rel='noopener noreferrer'>".html_safe
       - link_end = '</a>'.html_safe
-        %p
+      %p.gl-pl-6
         = s_("GitLabPages|When enabled, all attempts to visit your website through HTTP are automatically redirected to HTTPS using a response with status code 301. Requires a valid certificate for all domains. %{docs_link_start}Learn more.%{link_end}").html_safe % { docs_link_start: docs_link_start, link_end: link_end }
 
   .gl-mt-3