Further simplify test KDB module authdata code

Commit 94f7c9705879500b1dc8dda8592490efce05688f simplified the
generation of authdata elements, but left behind some unnecessary
conditionalization when assembling the elements into a list, causing a
Coverity defect.  Further simplify the code.

https://github.com/krb5/krb5/commit/d035dc269e80b58cb73fd2b644b06bc5fb53e9cb
Author: Greg Hudson <ghudson@mit.edu>
Commit: d035dc269e80b58cb73fd2b644b06bc5fb53e9cb
Branch: master
 src/plugins/kdb/test/kdb_test.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)