Get rid of XML related trove client bindings

We will no longer support XML for the trove API; it behooves us to
remove XML related code, and clean up the trove client.

Partially implements bp: destroy-xml-api
Change-Id: I58f95e81f3e4bc4bad277ff2a48abfced2b48199
Merge "Get rid of XML related trove client bindings"