Set keytab dir path in cdap-site.xml

Marking "done" since the cookbook is configuration agnostic.

Setting node['cdap']['cdap_site']['any.thing'] = 'contents' will create a property named "any.thing" with value "contents" in cdap-site.xml, so there's never any need to modify the cookbook on property changes.

I don't have much context on how the cookbook things work but earlier you mentioned that we will need to do something in cookbook for this.

ACK. You're right, I did. We just need to set this as a default.

PR: https://github.com/caskdata/cdap_cookbook/pull/223

We set this property when kerberos.auth.enabled and it'll be in the next cookbook release.