Version-check badge doesn't work if Referer header is not sent

Summary

check.svg (e.g. https://version.gitlab.com/check.svg?gitlab_info=eyJ2ZXJzaW9uIjoiMTEuOC4zIn0=) responds with a 404 request if no HTTP Referer header is sent.

Certain browser configurations (or extensions) may prevent a Referer header from being sent, which makes this version-check badge not render.

The following may have been caused by this: gitlab-ce#55751, gitlab-ce#52422

Relevant logs and/or screenshots