fix debug-on-exit remote_command

This MR fixes a small thing that slipped through when merging !2961 (merged): this MR should have consumed sylva-projects/sylva-elements/ci-tooling/ci-deployment-values!128 (merged), but for some reason this change was lost.

The new addition to run kubectl debug node commands from debug-on-exit, that we currently have in main does not work because of that:

+ kubectl -n sandbox debug node/bootstrap-1549765361-kubeadm-capm3-virt-control-plane --request-timeout=5s --profile=sysadmin --image registry.gitlab.com/sylva-projects/sylva-elements/container-images/kube-job:v1.0.17 -i -q -- chroot /host ss -apnm
Error from server (NotFound): namespaces "sandbox" not found

(e.g. https://gitlab.com/sylva-projects/sylva-core/-/jobs/8405588526#L1015)

This MR fixes that.

I'm also removing a set -vx that was useful during the development of this small evolution, but not relevant to keep.