Respect auth_to_local rules from hdfs configs (core-site.xml)

I defined the following rules:

auth_to_local = RULE:[1:$1@$0](ericlin@HADOOP)s/.*/eric/
auth_to_local = DEFAULT

in both krb5.conf on the impala daemon host as well as "Additional Rules to Map Kerberos Principals to Short Names" HDFS configuration in CM, impala daemon seems to ignore those rules from both places.

It would be good to get this fixed as it makes behaviour inconsistent between HS2 and Impala.

I think that auth_to_local_names is also ignored.