Fixed bug #62857 (bytea test failures)

Postgres 9.1+ test fixes. Tests were failing due to the default
standard_conforming_strings GUC being changed to on. Also the
pg_escape_bytea test was encoding the data before estabilishing
a connection, thus falling back to the old escaping type which
isn't properly handled by the backend when using a default
configuration.

I haven't updated the NEWS file as it's just test fixes.