ssh host key mismatch (again)

I'm having an issue where k0sctl and openssh seem to add conflicting entries to `~/.ssh/known_hosts` for the *same* host.

I first connect to the hostname `bne-nxt1-vr-1` using openssh. It connects OK and I see this entry appear in known_hosts:
```
bne-nxt1-vr-1 ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMeZMXleTWOrjmhYAwcfPZuv/CCkT0GLpIKPtjcWu+ip
```
if I then run k0sctl against the same hostname (using builtin `ssh` not `openSSH` config), I get an error:
```
- [SSH] bne-nxt1-vr-1: retrying aborted
not connected: client connect: can't connect: ssh: handshake failed: host key mismatch: knownhosts: key mismatch
```
If I remove the entry from known_hosts and try k0sctl again, it connects fine and I see this new entry in known_hosts (10.1.3.14 corresponds with the hostname):
```
10.1.3.14 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFAFlkzOExRFx4CF3vEs5/wWhtZx+HUoEW4fKoyBUfsbuMdS4N7Xri+J1XCI3jiOvvkzAz9gOeohmlo0cFOfJPg=
```

Additionally, I noticed k0sctl is adding the same entry to known_hosts repeatedly for this host (and others) e.g.
```
10.5.48.17 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBMbTbLidJyADmGw6uPgC+x16OlQrm3O6SeT3ujFLWjkNESI89mqVtuvfn21sQ4S1L8Fj6+GeOQQq+AofXD04/SE=
10.5.48.239 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFFq7/UAvpe1P/7g/FS1lS3ZYpUWNsWuEST2glfSbj+sabppXC3J7MVctv8lOw18xwoAcPApFJj7RQDw6hLFKUg=
10.5.48.17 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBMbTbLidJyADmGw6uPgC+x16OlQrm3O6SeT3ujFLWjkNESI89mqVtuvfn21sQ4S1L8Fj6+GeOQQq+AofXD04/SE=
10.5.48.239 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFFq7/UAvpe1P/7g/FS1lS3ZYpUWNsWuEST2glfSbj+sabppXC3J7MVctv8lOw18xwoAcPApFJj7RQDw6hLFKUg=
10.1.171.18 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBAcAH2R1wU9GVkqPz21LAHP002ouhFwVvgC9AJqpJV+SlSuCZsSd+ukgq96yHnAC+d1/KF4S7bvO0ZbqW9Z9Ecc=
10.5.48.239 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFFq7/UAvpe1P/7g/FS1lS3ZYpUWNsWuEST2glfSbj+sabppXC3J7MVctv8lOw18xwoAcPApFJj7RQDw6hLFKUg=
10.5.48.17 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBMbTbLidJyADmGw6uPgC+x16OlQrm3O6SeT3ujFLWjkNESI89mqVtuvfn21sQ4S1L8Fj6+GeOQQq+AofXD04/SE=
10.1.171.18 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBAcAH2R1wU9GVkqPz21LAHP002ouhFwVvgC9AJqpJV+SlSuCZsSd+ukgq96yHnAC+d1/KF4S7bvO0ZbqW9Z9Ecc=
10.5.48.239 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFFq7/UAvpe1P/7g/FS1lS3ZYpUWNsWuEST2glfSbj+sabppXC3J7MVctv8lOw18xwoAcPApFJj7RQDw6hLFKUg=
10.5.48.17 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBMbTbLidJyADmGw6uPgC+x16OlQrm3O6SeT3ujFLWjkNESI89mqVtuvfn21sQ4S1L8Fj6+GeOQQq+AofXD04/SE=
10.1.171.18 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBAcAH2R1wU9GVkqPz21LAHP002ouhFwVvgC9AJqpJV+SlSuCZsSd+ukgq96yHnAC+d1/KF4S7bvO0ZbqW9Z9Ecc=
10.5.48.239 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFFq7/UAvpe1P/7g/FS1lS3ZYpUWNsWuEST2glfSbj+sabppXC3J7MVctv8lOw18xwoAcPApFJj7RQDw6hLFKUg=
10.5.48.17 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBMbTbLidJyADmGw6uPgC+x16OlQrm3O6SeT3ujFLWjkNESI89mqVtuvfn21sQ4S1L8Fj6+GeOQQq+AofXD04/SE=
10.1.171.18 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBAcAH2R1wU9GVkqPz21LAHP002ouhFwVvgC9AJqpJV+SlSuCZsSd+ukgq96yHnAC+d1/KF4S7bvO0ZbqW9Z9Ecc=
10.1.3.14 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFAFlkzOExRFx4CF3vEs5/wWhtZx+HUoEW4fKoyBUfsbuMdS4N7Xri+J1XCI3jiOvvkzAz9gOeohmlo0cFOfJPg=
10.5.48.239 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFFq7/UAvpe1P/7g/FS1lS3ZYpUWNsWuEST2glfSbj+sabppXC3J7MVctv8lOw18xwoAcPApFJj7RQDw6hLFKUg=
10.5.48.17 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBMbTbLidJyADmGw6uPgC+x16OlQrm3O6SeT3ujFLWjkNESI89mqVtuvfn21sQ4S1L8Fj6+GeOQQq+AofXD04/SE=
10.1.3.14 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBFAFlkzOExRFx4CF3vEs5/wWhtZx+HUoEW4fKoyBUfsbuMdS4N7Xri+J1XCI3jiOvvkzAz9gOeohmlo0cFOfJPg=
10.1.171.18 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBAcAH2R1wU9GVkqPz21LAHP002ouhFwVvgC9AJqpJV+SlSuCZsSd+ukgq96yHnAC+d1/KF4S7bvO0ZbqW9Z9Ecc=
```
I'm using k0sctl v0.21.0 on MacOS 15.1.1

If I use `openSSH` rather than `ssh` I don't have this issue, however it is much slower that way. It would be nice not to have to call out to openssh.

Last time [I had a similar issue](https://github.com/k0sproject/k0sctl/issues/717) the problem was in the [rig](https://github.com/k0sproject/rig) library. I mean no disrespect to the maintainers of rig, but I wonder if it's not yet mature enough for use in k0sctl?

Reproduce the issue with k0sctl v0.21.0 using the built-in `ssh` path, comparing it with `openSSH` and inspecting the referenced rig library. Trace how the hostname and IP address are written to `~/.ssh/known_hosts`; done means the built-in path accepts the same host identity as OpenSSH and does not append duplicate entries.

Written by the indexing model from the issue text.