[INTERNAL] removed IProgressMonitor usage from StopManager

The manual cancellation is now replaced with a timeout.

Change-Id: Ia3263500bad8b5090938cce06664e4f549908374
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1427
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>