[Database] Set bytea_output to match pg_unescape_bytea().

* In newer versions of PG, a "hex" escaping format is used, which
  totally breaks things like SqlBagOStuff since the pg_unescape_bytea
  function still works the old way (it does not use a DB handle).
  Setting the format to the old way via SET fixes this.

Change-Id: I9f5a64922acd2d954880790f42ba4efafaed314e