browser onboarding: 8.5 security level image includes English text

The security level image that is shown on the "updated for Tor Browser 8.5" Security onboarding page includes a screenshot of the Security Level doorhanger that was taken when running in the en-US locale. That means we will show English text for all locales. We should find a different solution in the long run.

This is the image: https://gitweb.torproject.org/tor-browser.git/plain/browser/extensions/onboarding/content/img/figure_tor-security-level.png?h=tor-browser-60.6.1esr-8.5-1