Update delete group message

What does this MR do and why?

Update delete group message

• update to account for projects in group that are security policy projects
• list out linked containers to spp
• use helper in view and service
• add tests

Changelog: added

EE: true

References

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Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Upload a GitLab Ultimate
2. Enable the feature flag echo "Feature.enable(::reject_security_policy_project_deletion_groups)" | rails c
3. Navigate to a group with a security policy project in it => Settings => General => Advanced => Delete group
4. Verify the card is updated with the projects and links and delete button disabled

Related to #512047 (closed)