- drop versions < 1.22 in the etcd map
- use 3.5.9-0 for >= 1.22 versions
- make the minimum version for external etcd 3.4.13-4 and max 3.5.9-0
- update images_test to not rely on a pinned etcd version in tests
note: the image 3.4.18-0 was never released in registry.k8s.io!