Adjust Jenkinsfile for move of releng.aggregator to github

Change-Id: I5081159d30c49c869f1f5b8d570abee43419996d
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.team/+/190641
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Alexander Kurtakov <akurtako@redhat.com>
1 file changed