CI: Actually read in CILIUM_IMAGE when splitting it
CI: Actually read in CILIUM_IMAGE when splitting it

We added setting the component parts of the image (registry and tag) to
ensure that these are consistent. This is currently only relevant to the
upgrade test but may be needed in the future as we set more of these
variables via the CILIUM_IMAGE variable.

fixes 1b75c08cc5f12758e7d5e92121d04a25da854c0f

Signed-off-by: Ray Bejjani <7f525154e857f3d57a641a83dddc584f42addc6a@isovalent.com>

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