k8s: Guard against failed cilium client setup
k8s: Guard against failed cilium client setup

We ensure a k8s cilium client is created with a Once.Do but in the case
that we encounter an error in the Once, other threads blocked on it or
later calls to this function will dereference a nil in the return.

Signed-off-by: Ray Bejjani <7f525154e857f3d57a641a83dddc584f42addc6a@covalent.io>

tgraf/cilium,scanf/cilium,tgraf/cilium,eloycoto/cilium,michi-covalent/cilium,tgraf/cilium,cilium-team/cilium,tklauser/cilium,tklauser/cilium,eloycoto/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium,tgraf/cilium,cilium/cilium,scanf/cilium,tklauser/cilium,eloycoto/cilium,eloycoto/cilium,scanf/cilium,cilium/cilium,cilium-team/cilium,michi-covalent/cilium,tgraf/cilium,tgraf/cilium,eloycoto/cilium,michi-covalent/cilium,scanf/cilium,cilium/cilium,eloycoto/cilium,cilium/cilium,tklauser/cilium,scanf/cilium,michi-covalent/cilium,eloycoto/cilium,scanf/cilium,scanf/cilium