Fix differnece of storage used in UI

What does this MR do and why?

It fixes a bug in the namespace storage UI where the displayed total storage at the top block is different from the projects' total storage in the projects table below.

Screenshots or screen recordings

before	after

How to set up and validate locally

• Enable update_storage_usage_design feature flag locally
• Have a group where you're maintainer/admin of
• Create a project within that group
• Check group's usage quota's > Storage

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.

Related to #362924 (closed)