cli: cleanups for pre-v1.15 removal
Remove a bit of unused code that was left behind by https://github.com/cilium/cilium/commit/8cd07122737522b0f8f7ada633ee1e3f07708e48 ("cli: require Cilium v1.15").
Remove a bit of unused code that was left behind by https://github.com/cilium/cilium/commit/8cd07122737522b0f8f7ada633ee1e3f07708e48 ("cli: require Cilium v1.15").