Fix log message containing invalid access latency and retention policy values

Addresses an issue in which log messages would show values for
access latency and retention policy from uninitialized fields,
rather than the actual values of the file the log message is
refering to.

The regression was introduced when these fields got deprecated
in storage info. dCache doesn't make use of the fields anymore,
however they still appear in the toString version of storage info
and thus appear in various log outputs and error message.

Target: trunk
Request: 2.7
Request: 2.6
Require-notes: yes
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6273/