Update doc, default values and kube.tf with recent changes to cluster_autoscaler_version, initial_k3s_channel and var sys_upgrade_controller_version

[janfrederik]

#1512 introduced a new var sys_upgrade_controller_version.

• Corrected the description, which was an incorrect copy-paste from another var.
• Added the var to kube.tf.example

#1506 reverted cluster-autoscaler back to the community version. However, the default version for var cluster_autoscaler_version (1.31.1), does not correspond to the new default initial_k3s_channel ("stable", which is currently still 1.30) and the doc says these versions should correspond. So I put version 1.30.3 as default. This is in line with the initial_k3s_channel and includes the patch for the Hetzner deprecation of CX11.

Added csi_driver_smb_version to kube.tf.example

[mysticaltech]

Thanks @janfrederik, appreciate this very much.