[docker] Add few kerberos packages in py3 Dockerfile (#2797)
[docker] Add few kerberos packages in py3 Dockerfile (#2797)

- 'krb5-config', 'krb5-user' packages were missed when the py2 and py3 Dockerfiles were swapped.
cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue,cloudera/hue