[API] Remove unnecessary parameter from Saros/I's IProgressMonitor

The ISubMonitor implementation in Saros-I is a hack to reuse more of the
code.
There is no Submonitoring facility in IntelliJ and it will be removed

Change-Id: I81737b6e958eecc97d88ff27704427230f9b24e5
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1702
Tested-by: Jenkins CI
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>