Remove duplicate error messages from cli commands

Since we never use the cobras "SilenceErrors" or "SilenceUsage",
a command executed with "cmd.Execute()" will never return an error
without printing it.

The current behavior results in all error messages being printed twice:

Example:

$ kubectl abc
Error: unknown command "abc" for "kubectl"
Run 'kubectl --help' for usage.
unknown command "abc" for "kubectl"

This applies to all cli commands using Cobra. To verify, follow the code
path of the Execute function:

https://github.com/spf13/cobra/blob/c439c4fa0937/command.go#L793
Signed-off-by: Odin Ugedal <odin@ugedal.com>

cmd/cloud-controller-manager/controller-manager.go

@@ -20,7 +20,6 @@ limitations under the License.
 package main
 
 import (
-	"fmt"
 	"math/rand"
 	"os"
 	"time"
@@ -48,7 +47,6 @@ func main() {
 	defer logs.FlushLogs()
 
 	if err := command.Execute(); err != nil {
-		fmt.Fprintf(os.Stderr, "error: %v\n", err)
 		os.Exit(1)
 	}
 }