Windows::killRecursively() invokes process killers after completion.
Resolves https://issues.jenkins-ci.org/browse/JENKINS-19156

Signed-off-by: Oleg Nenashev <nenashev@synopsys.com>
Merge branch 'jenkins_19156_windows_processkiller' of https://github.com/synopsys-arc-oss/jenkins into pr903