fix(files): Adjust NavigationQuota for Nextcloud 30 design

[susnux]

Summary

The quota still was using 44px size, so this fixes it by using variables instead.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• [ ] Tests (unit, integration, api and/or acceptance) are included
• [ ] Screenshots before/after for front-end changes
• [x] Documentation (manuals or wiki) has been updated or is not required
• [x] Backports requested where applicable (ex: critical bugfixes)