Adjust Jenkinsfile for move of releng.aggregator to github

Change-Id: I4150ac331125ed22f1dfdb2e8fdcefcaeb57bbeb
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>
Reviewed-on: https://git.eclipse.org/r/c/equinox/rt.equinox.p2/+/190614
Tested-by: Equinox Bot <equinox-bot@eclipse.org>
1 file changed