fix: honour -o json/custom across missing and broken commands

[alubbock]

Several commands ignored the -o json and -o custom flags, always
printing plain text regardless. One command (kubernetes cluster remove)
had a latent bug where -o json also triggered the custom formatter.

Missing output format handling (always printed plain text):

• kubernetes node-pool instance-delete
• kubernetes cluster remove (also had WriteCustomOutput inside the
  "json" case, so -o json produced both outputs)
• apikey remove / apikey set
• instance public-ip / instance recovery
• kubernetes update-kubeconfig
• network show

Also fixed in instance recovery: a fmt.Println("Instance ID is: …") that fired before the API call, unconditionally, on every
invocation.