vcluster k8s version set

[ric-hincapie]

Change:
control exactly the k8s version of virtual clusters (vclusters).

Description:
When defining k8s_version variable at config.yaml, it was only used to define it for the k3d cluster (the base cluster), but not for vclusters, where tsb actually runs. The vcluster version was the default one v1.25.14 of vcluster vcluster version 0.16.3.

[eitansuez]

if i had to guess, i would expect a vcluster create command to use the k8s version of the host cluster.
as a test, i just stood up an environment. kubectl version tells me that the host cluster's k8s version is 1.27.6 (what i set it to in my config.yaml file). if i switch contexts to one of the vclusters, either through the vcluster connect command or with k config use-context and repeat the kubectl version command the server version shown in the output is 1.27.6.

[eitansuez]

i just reviewed the vcluster create command logic. if the --kubernetes-version flag is not provided explicitly, it defaults to the k8s version of the host cluster, obtained from the client config. i don't think this code change is necessary.