fix usage of command in makefile on Ubuntu

Make will try to avoid launching a shell to execute simple commands;
this breaks for shell builtins, such as 'command'.

Signed-off-by: Angel Misevski <amisevsk@redhat.com>

Makefile

@@ -110,7 +110,7 @@ update_crds: _update_crds
 uninstall:
 # It's safer to delete all workspaces before deleting the controller; otherwise we could
 # leave workspaces in a hanging state if we add finalizers.
-ifneq ($(shell command -v kubectl),)
+ifneq ($(shell command -v kubectl 2> /dev/null),)
 	kubectl delete workspaces.workspace.che.eclipse.org --all-namespaces --all
 else
 	$(info WARN: kubectl is not installed: unable to delete all workspaces)