zopewsgi: Fix msec log format

So that msec=1 is logged as ",001" and not as ",1".
3 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.PerformanceTest-Master

00:29:09

passed SlapOS.Eggs.UnitTest-Master.Python2

00:17:31

passed SlapOS.Eggs.UnitTest-Master.Python3

00:19:28