kojira: remove duplicate Kerberos configuration boilerplate
eea730300a5e6b40bf8c041a71b3f3c567de4abe added a dedicated section for
Kerberos authentication to kojira.conf. It refers to the canonical
location /etc/kojira/kojira.keytab.
Prior to this change, there were two "kerberos" sections in kojira.conf.
Remove the older stale one, since that refers to the old
"/etc/kojira.keytab" file path, and
f232e491941e888e4713a815148a00736445e7d4 defaults to
/etc/kojira/kojira.keytab instead.