fix(billing): adjust usage page loading spinner logic TASK-1321

[jamesrkiger]

🗒️ Checklist

1. run linter locally
2. update all related docs (API, README, inline, etc.), if any
3. draft PR with a title <type>(<scope>)<!>: <title> TASK-1234
4. tag PR: at least frontend or backend unless it's global
5. fill in the template below and delete template comments
6. review thyself: read the diff and repro the preview as written
7. open PR & confirm that CI passes
8. request reviewers, if needed
9. delete this section before merging

📣 Summary

Fix error that was causing infinite loading spinner on usage page for non-Stripe instances.

📖 Description

The usage page was expecting addons context to complete loading before switching from loading spinner to displaying page contents. However, the usage page needs to be usable on non-Stripe instances addons context never loads on such instances. I have adjusted the logic for checking whether or not the page is ready to display accordingly. At the same time, I also removed the memoization for this logic, as it was unnecessary and only used in one place.

👀 Preview steps

1. Access the usage page with Stripe disabled
2. On main, you will get an infinite loading spinner
3. On this branch, you will see the usage page as expected