Install a kyua.conf based on the one in devel/kyua.

The kyua.conf from examples doesn't match the expected config and
contains a lot of undesirable entries such as setting the architecture
to amd64 explicitly.

Reported by: arichardson (missing config)
Reviewed by: emaste
Obtained from: CheriBSD
Differential Revision: https://reviews.freebsd.org/D24267