The kerberized minicluster is enabled by setting IMPALA_KERBERIZE=true in impala-config-*.sh.
After setting it you must run ./bin/create-test-configuration.sh then restart the minicluster (e.g. with testdata/bin/run-all.sh).
The Kerberized minicluster requires a KDC to be setup and configured and service users to be added to the keytab at $KRB5_KTNAME. This step is not automated. experimental-kerberos-setup.sh automates some of the setup but is experimental at this point.
Not all minicluster services actually work or are kerberized at this point. I was able to run queries against pre-existing HMS tables stored in HDFS.
Kerberos is finicky about hostnames - you may need to tweak your /etc/hosts to get hosts to authenticate if kerberos thinks that hostnames are distinct.
Killing minicluster services seems to be broken when using a kerberized minicluster. You may need to manually kill the services.