Update total storage size when changing size of artifacts

What does this MR do?

Fixes regression for storage size introduced by !17839 (merged)

Increasing artifacts size needs to increase total storage size, too.

Are there points in the code the reviewer needs to double check?

Not that I know of.

Why was this MR needed?

To fix a bug.

Screenshots (if relevant)

n/a

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conforms to the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

This fixes one of things reported in #49368 (moved)