dms: disable open button in PDF viewer

It does not make any sense to open PDF files from this gadget.

Also remove duplicate line with documentProperties
3 jobs for feat/datetime3 in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-TestRunner1

06:15:04

passed ERP5.PerformanceTest-TestRunner1

02:52:33

failed ERP5.UnitTest-TestRunner1

07:55:54