verify_krb5_conf: sort entries, remove duplicates

Change-Id: I23dc60b4c48bcf08ed9ad687ee792366b25db3d7
(cherry picked from commit 8676b27b2608423a5cafa986d3f346cb6cb4663a)
verify_krb5_conf: add missing entries

Change-Id: I45761e046801fcdb101b82b081a7b1fe65d882ee
(cherry picked from commit 20aaa7c37aa63fb60eee7b57f143b8690bf7858f)