Remove unused fields from storage query

What does this MR do and why?

It remove the unused fields from namespace_storage.query.graphql:

• namespace.name
• project.repositorySizeExcess
• project.actualRepositorySizeLimit
• project.statistics.commitCount

For a namespace with 6 projects, the response size reduced by 0.6 KB and reduced one SQL query per project similar to this query:

SELECT "project_statistics".* FROM "project_statistics" WHERE "project_statistics"."project_id" = 29 LIMIT 1

Screenshots or screen recordings

N/A

How to set up and validate locally

• Checkout the branch
• Navigate to a group's Usage Quoats > Storage tab

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 #431177