Removed upload_size from storage_size

What does this MR do and why?

Removes upload_size from storage_size calculation.

We currently track upload_size on project_statistics records, which get added to the project_statistics#storage_size total column.

This column is then used at the root namespace level within the RootStorageStatistics which is the total storage across a namespace.

ref: https://gitlab.com/gitlab-org/gitlab/-/issues/367995

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