[api][prod] Add sentry error logging about system800

[guyrt]

This looks like it could raise security issues if we aren't careful: sentry adds local context info which may contain PII. As long as we set up scrubbing correctly, we're good. But it's worth keeping in mind, especially since it's easy to forget to update scrub keys (he says, from unfortunate experience).

I'm happy to work on this, but other question for clarification is whether we want to use a shared sentry or make this part of the config for new hosters. If so, it's yet another thing to set up. Thoughts?

[oelachqar]

Agreed regarding the security risk, which makes me think that we have the same issue with flower logging, we should fix that as well...

If it's easy to make sentry "optional", maybe we can create our own account and use it for our own development to help find bugs more quickly. Hosters who are interested can provide their own keys and sentry account while the others can just ignore it