Bugfixes

- Increase the length of the strings for the task column in dbsbuffer_workflow to make it
  consistent with the task in wmbs_workflow
- Make the DBS3Upload component less verbose in INFO level
- Change the default DBS3 upload URL to cmsweb-testbed
Merge pull request #4602 from dballesteros7/fix-dbsbuffer-size

Bugfixes for size of DBSBuffer fields and debug messages