Remove XenAPI driver deprecation warning log message

This reverts commit 8404694daec4febffd1665ee5d3753177031f1d5. CI has
been running for XenAPI and all requirements have been met such that we
will not be removing XenAPI.

Change-Id: I544bb642fdd72aef28bcaf809c34d5db43ce0937
Merge "Remove XenAPI driver deprecation warning log message"