Fixes annual price showing as a large monthly amount

[srartese]

Checklist

1. If you've added code that should be tested, add tests
2. If you've changed APIs, update (or create!) the documentation
3. Ensure the tests pass
4. Make sure that your code lints and that you've followed our coding style
5. Write a title and, if necessary, a description of your work suitable for publishing in our release notes
6. Mention any related issues in this repository (as #ISSUE) and in other repositories (as kobotoolbox/other#ISSUE)
7. Open an issue in the docs if there are UI/UX changes

Description

This fixes the current state of the annual toggle on the plans page which has a high monthly rate when it should show a cheaper monthly amount. By users subscribing to an annual plan they get a cheaper monthly rate compared to subscribing to a monthly plan.