refactor: Re-organize the delegates to namespace_settings from group

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What does this MR do and why?

refactor: Re-organize the delegates to namespace_settings from group

• Consolidate delegate calls in Group model using multi-line syntax for better readability and maintainability of delegation patterns
• Replace custom normalize_default_branch_name with the utility module NullifyIfBlank

While working on other MRs, I noticed this potential for refactoring, e.g. !199423 (merged)

Changelog: other

🛠️ with ❤️ at Siemens

References

Screenshots or screen recordings

Only refactoring changes in the backend . No change in behavior.

How to set up and validate locally

1. Run the tests

bundle exec rspec spec/models/namespace_setting_spec.rb spec/models/group_spec.rb

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

MR Checklist (@gerardo-navarro)

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the style guides
• Conforms to the javascript style guides
• Conforms to the database guides
• Conforms to the merge request performance guidelines