feat: stop caching prospectus app-data.json

[srwang]

A retry after this revert, targeting only the specific file that needs to get updated.

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For WS-4498

This is to ensure that page-data is cleared on the user's browser between builds, preventing any reloading behavior triggered by the browser being unable to find the most recent version of page-data.

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Make sure that the following steps are done before merging:

• Have a Site Reliability Engineer review the PR if you don't own all of the services impacted.
• If you are adding any new default values that need to be overridden when this change goes live, update internal repos and add an entry to the top of the CHANGELOG.
• Performed the appropriate testing.
• Think about how this change will affect Open edX operators and update the wiki page for the next Open edX release if needed