[JIRA] (BIT-1283) Bro crashes when using &encrypt

I don't remember if we discussed this already at some point, which may
have then led to the deprecation. I'm fine either way. It's a nice
capability in principle, but given that files aren't our main logging
mechanism anymore, it's unlikely anybody is actually using it. So in
the spirit of removing complexity, maybe that's indeed the right thing
to do.

Indpendent of that, an item for the todo list is adding encryption
support to the logging framework. But that needs a larger project, I'm
hoping that we can do better than just encrypt a whole file with a
single key. Would be nice to give out partial access in some form, but
not quite sure how that would look like.