We should be able to detect if rdns is enabled by default. See this API: https://web.mit.edu/kerberos/krb5-1.16/doc/appdev/refs/api/krb5_get_profile.html

We should parse out a tri-state of RDNS=true/false/unknown. If the
state is not unknown, we stop ourselves making statements/assertions about
setting it.

When running under verbose mode, we should print out all keys/values from the profile if possible. This will let us show libkrb5's idea of its configuration without us having to bake in assumptions about how to find the config file. Since there are loadable plugins that teach libkrb5 different ways to get configs, this technique would protect us from them.