Converts storage_quota.scss into a page bundle

What does this MR do and why?

Addresses Convert stylesheets/pages/storage_quota.scss in... (#239880 - closed), part of Extract Page Specific CSS Files (&3694) epic.

Convert app/assets/stylesheets/pages/storage_quota.scss into a page bundle that is only included on relevant pages.

This file was responsible for storage graph atop projects/usage_quotas, e.g.:

Screenshots or screen recordings

theme	before	after
white
dark

How to set up and validate locally

Open a project Usage Quotas page and check the horizontal graph atop the page http://127.0.0.1:3000/h5bp/html5-boilerplate/-/usage_quotas#storage-quota-tab

MR acceptance checklist

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