contrib/backporting: add environment variables to set ORG and REPO
contrib/backporting: add environment variables to set ORG and REPO

Having these environment variables allows the cherry-pick script to be
used on other projects that are not Cilium.

Signed-off-by: André Martins <bc9800b9d52a24cce72a73dd528afed53f10e5fc@cilium.io>

cilium/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,tklauser/cilium,michi-covalent/cilium,michi-covalent/cilium,tklauser/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium,cilium/cilium,michi-covalent/cilium