Add project and group max artifacts size fields

What does this MR do?

This adds the max_artifacts_size fields on their respective pages for project and group level settings.

Documentation has also been updated to include instructions about the new settings.

Solves #21688 (closed)

Screenshots

On the project settings page (field only visible to admins):

On the group settings page (section only visible to admins):

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team