fix(kubernetes): prune opt-in

making it opt out can result in dangerous moments when the local sources are not
recent enough.

As this could kill entire clusters, we are going to make it opt in

cmd/tk/workflow.go

@@ -32,7 +32,7 @@ type workflowFlagVars struct {
 func workflowFlags(fs *pflag.FlagSet) *workflowFlagVars {
 	v := workflowFlagVars{}
 	fs.StringSliceVarP(&v.targets, "target", "t", nil, "only use the specified objects (Format: <type>/<name>)")
-	fs.BoolVarP(&v.prune.Prune, "prune", "p", true, "automatically remove objects from the cluster that are not present in Jsonnet anymore")
+	fs.BoolVarP(&v.prune.Prune, "prune", "p", false, "automatically remove objects from the cluster that are not present in Jsonnet anymore")
 	fs.BoolVar(&v.prune.AllKinds, "prune-all-kinds", false, "prune all object kinds, not just the most common ones (much slower)")
 	return &v
 }