Support all JDBC-HiveServer2 authentication modes on a secure cluster

Currently, HiveServer2 logs in with its keytab only if hive.server2.authentication is set to KERBEROS. However, hive.server2.authentication is config that determines the auth type an end user will use while authenticating with HiveServer2. There is a valid use case of user authenticating with HiveServer2 using LDAP for example, while HiveServer2 runs the query on a kerberized cluster.