Include Pipeline Artifacts on storage usage page

What does this MR do?

Related to #241179 (closed)

Include pipeline artifacts size in the usage quota by combining it with the build artifacts size and changing the label to just "Artifacts".

Screenshots

Before

After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• [-] Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done