Migrate custom attributes card to ViewComponent

Changelog: changed

app/views/shared/_custom_attributes.html.haml

 - return unless custom_attributes.present?
 
-.card
-  .card-header
+= render Pajamas::CardComponent.new(body_options: { class: 'gl-py-0' }) do |c|
+  - c.header do
     = link_to(_('Custom Attributes'), help_page_path('api/custom_attributes.md'))
-  %ul.content-list
-    - custom_attributes.each do |custom_attribute|
-      %li
-        %span.light
-          = custom_attribute.key
-        %strong
-          = custom_attribute.value
+  - c.body do
+    %ul.content-list
+      - custom_attributes.each do |custom_attribute|
+        %li
+          %span.light
+            = custom_attribute.key
+          %strong
+            = custom_attribute.value