Modifies Package Registry group settings

What does this MR do and why?

Make changes to Package Registry group settings

• Changes title & description
• Removes flex-box for Exceptions toggle

This MR is part of series of MRs related to #363424 (closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Visit 'Group' > 'Settings' > 'Packages & Registries'
2. Confirm 'Package Registry' section has new title, changed description & layout for 'Exceptions' is changed

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

spec/features/groups/settings/user_searches_in_settings_spec.rb

@@ -48,6 +48,6 @@
       visit group_settings_packages_and_registries_path(group)
     end
 
-    it_behaves_like 'can highlight results', 'Use GitLab as a private registry'
+    it_behaves_like 'can highlight results', 'Allow packages with the same name and version'
   end
 end