move deprecation entry to the original file

It seems that verifyHostCertificateChain was only used within xrootd.properties
and not in dcache.properties.

* Move the deprecation entry for verifyHostCertificateChain to
  xrootd.properties, where that property came from.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>