uses_enhanced_dns_logic: False items in server descriptors are wrong/highly misleading

A lack of eventdns in the server descriptor gets translated to uses_enhanced_dns_logic: False. However, that is wrong/highly misleading. Here is what the spec says right now:

"eventdns" bool NL

[At most once]

Declare whether this version of Tor is using the newer enhanced dns logic. Versions of Tor with this field set to false SHOULD NOT be used for reverse hostname lookups.

[This option is obsolete.  All Tor current relays should be presumed to have the evdns backend.]

It seems a lack of that field should get translated to True, nowadays at least, and only be False in case of eventdns false.