CI: K8sServicesTest consistenly uses global DefaultNamespace
CI: K8sServicesTest consistenly uses global DefaultNamespace

This test mixed literal "default" and the global variable. It now uses
only the global variable.

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

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