Updates memory size labels to use B instead of bytes

What does this MR do and why?

Updates memory size labels for bytes to be just B, as was discussed in slack. This is a "sibling" update to !120333 (comment 1399483337) MR, where we update backend labels to use B instead of Bytes.

Related to #412932

Screenshots or screen recordings

Before	After

How to set up and validate locally

Open a namespace storage Usage Quotas (e.g. /groups/gitlab-org/-/usage_quotas#storage-quota-tab) and see how the bytes labels are displayed.

MR acceptance checklist

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