hubble/server: close the socket when api.SetDefaultPermissions fail
hubble/server: close the socket when api.SetDefaultPermissions fail

Also fail fast when o.Listener is already configured as it is a
programming or configuration issue.

Signed-off-by: Alexandre Perrin <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@kaworu.ch>

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