runtime: change io/ioutil to io/os packages

Change io/ioutil to io/os packages because io/ioutil package
is deprecated from 1.16:

Discard => io.Discard
NopCloser => io.NopCloser
ReadAll => io.ReadAll
ReadDir => os.ReadDir
ReadFile => os.ReadFile
TempDir => os.MkdirTemp
TempFile => os.CreateTemp
WriteFile => os.WriteFile

Details: https://go.dev/doc/go1.16#ioutil

Fixes: #3265

Signed-off-by: bin <bin@hyper.sh>

src/runtime/cmd/kata-runtime/kata-check_generic_test.go

@@ -9,7 +9,6 @@
 package main
 
 import (
-	"io/ioutil"
 	"os"
 	"testing"
 
@@ -19,7 +18,7 @@ import (
 func testSetCPUTypeGeneric(t *testing.T) {
 	assert := assert.New(t)
 
-	tmpdir, err := ioutil.TempDir("", "")
+	tmpdir, err := os.MkdirTemp("", "")
 	assert.NoError(err)
 	defer os.RemoveAll(tmpdir)