module(apt_key): don't catch `SystemExit`

If we do this, we risk outputting two JSON payloads, which will be
unparsable.
module(nagios): don't catch `SystemExit`

If we do this, we risk outputting two JSON payloads, which will be
unparsable.
Merge pull request #5162 from JensRantil/fix-corrupt-module-outputs

More don't catch `SystemExit`