Enable feature spec for group unarchive settings

After General settings page of archived groups return... (#558811 - closed) has been fixed. We can re-enable the feature spec for group unarchive settings

https://gitlab.com/gitlab-org/gitlab/blob/9856952e7160e08ebcaa55caf853f5bf5a5fca52/spec/features/groups/group_settings_spec.rb#L323-L339

Implementation Guide

1. Apply the following patch:

Index: spec/features/groups/group_settings_spec.rb
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/spec/features/groups/group_settings_spec.rb b/spec/features/groups/group_settings_spec.rb
--- a/spec/features/groups/group_settings_spec.rb	(revision 9856952e7160e08ebcaa55caf853f5bf5a5fca52)
+++ b/spec/features/groups/group_settings_spec.rb	(date 1754072217106)
@@ -320,8 +320,7 @@
       specify { expect(page).not_to have_button(s_('GroupProjectUnarchiveSettings|Unarchive')) }
     end
 
-    context 'when group is archived',
-      skip: 'Returns a 404 in CE due to a bug: https://gitlab.com/gitlab-org/gitlab/-/issues/558811' do
+    context 'when group is archived' do
       before do
         subgroup.archive