enhance(cloud-function): return 404.json if index.json not found

[caugner]

Summary

(MP-1356)

Problem

We usually show a nice 404 page (e.g. https://developer.allizom.org/en-US/404), but this does not apply for Blog (https://developer.allizom.org/en-US/blog/404/) and Curriculum (https://developer.allizom.org/en-US/curriculum/404/). The correct 404 page shows up shortly, and is then replaced by an empty page with only header and footer.

Solution

Return 404.json for missing index.json requests.

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Screenshots

Before

After

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How did you test this change?

Will deploy to stage on July 10.