Run e2e tests without devMode enabled

[patcon]

Re-ticketed from https://github.com/pol-is/polis/pull/550

This would likely give us more confidence in the test results, since we're on more production-like code paths.

Perhaps ideally we should test both production and devmode?

Or rather, if we have docker, which can give us a very production-like environment, do we still need to worry too much about devMode? (Maybe we should do an audit to see what's actually different)