k8s: Do not error out if k8s node does not have a CIDR assigned
k8s: Do not error out if k8s node does not have a CIDR assigned

Deriving the CIDR based on the node CIDR should be optional. Do not
error out if the k8s node does not specify a CIDR to use. The user
can always specify it manually.

Signed-off-by: Thomas Graf <5f50a84c1fa3bcff146405017f36aec1a10a9e38@cilium.io>

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