Windows: Reduce RDR Object Lifetime

Adjust the redirector object lifetime from 10 minutes (600 seconds)
to 20 seconds.  The object lifetime is how long an object can remain
idle before garbage collection is permitted.

Change-Id: I8db89bfb0ccd40e9295dcbb30fbc2c96813d9fc9
Reviewed-on: http://gerrit.openafs.org/8954
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>