### What would you like to be added?

As of go 1.22, for string to bytes conversion, we can replace the usage of `unsafe.Slice(unsafe.StringData(s), len(s))` with type casting `[]bytes(str)`, without the worry of losing performance.

As of go 1.22, string to bytes conversion `[]bytes(str)` is faster than using the `unsafe` package. Both methods have 0 memory allocation now.


I saw at least two places in the codebase still using the `unsafe` way:
+ https://github.com/kubernetes/kubernetes/blob/e342ab05bb903519350cedac784898529eaef06b/staging/src/k8s.io/apiserver/pkg/authentication/token/cache/cached_token_authenticator.go#L277-L286

+ https://github.com/kubernetes/kubernetes/blob/e342ab05bb903519350cedac784898529eaef06b/staging/src/k8s.io/apiserver/pkg/storage/value/encrypt/envelope/kmsv2/envelope.go#L511-L520

Here's my benchmark results, comparing two ways of conversion:

```bash
╰─○ go test -v -run=none -bench=. -benchmem=true
goos: darwin
goarch: amd64
pkg: example.com/m/v2
cpu: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
BenchmarkStringToBytesUnsafe
BenchmarkStringToBytesUnsafe-12         1000000000               0.5636 ns/op          0 B/op          0 allocs/op
BenchmarkStringToBytesCasting
BenchmarkStringToBytesCasting-12        1000000000               0.2548 ns/op          0 B/op          0 allocs/op
PASS
ok      example.com/m/v2        1.448s
```

My test code:
```
package main

import (
	"testing"
	"unsafe"
)

const (
	str = "some random string"
)

func toBytes(s string) []byte {
	// unsafe.StringData is unspecified for the empty string, so we provide a strict interpretation
	if len(s) == 0 {
		return nil
	}
	// Copied from go 1.20.1 os.File.WriteString
	// https://github.com/golang/go/blob/202a1a57064127c3f19d96df57b9f9586145e21c/src/os/file.go#L246
	return unsafe.Slice(unsafe.StringData(s), len(s))
}

func toBytesRaw(s string) []byte {
	return []byte(s)
}

func BenchmarkStringToBytesUnsafe(b *testing.B) {
	for i := 0; i < b.N; i++ {
		_ = toBytes(str)
	}
}

func BenchmarkStringToBytesCasting(b *testing.B) {
	for i := 0; i < b.N; i++ {
		_ = toBytesRaw(str)
	}
}
```


### Why is this needed?

+ Kubernetes as of now is built with go 1.22, in go 1.22 type casting is faster than unsafe, regarding **only** string to bytes conversion
+ We can make string to bytes conversion faster with type casting
+ We don't need to be 'unsafe' anymore
As of go 1.22, there's no need to use the unsafe package for string to bytes conversion
This is a GitHub Issue
repo:kubernetes
owner:kubernetes
Title : As of go 1.22, there's no need to use the unsafe package for string to bytes conversion
Issue date:

--- start body ---
### What would you like to be added?

As of go 1.22, for string to bytes conversion, we can replace the usage of `unsafe.Slice(unsafe.StringData(s), len(s))` with type casting `[]bytes(str)`, without the worry of losing performance.

As of go 1.22, string to bytes conversion `[]bytes(str)` is faster than using the `unsafe` package. Both methods have 0 memory allocation now.


I saw at least two places in the codebase still using the `unsafe` way:
+ https://github.com/kubernetes/kubernetes/blob/e342ab05bb903519350cedac784898529eaef06b/staging/src/k8s.io/apiserver/pkg/authentication/token/cache/cached_token_authenticator.go#L277-L286

+ https://github.com/kubernetes/kubernetes/blob/e342ab05bb903519350cedac784898529eaef06b/staging/src/k8s.io/apiserver/pkg/storage/value/encrypt/envelope/kmsv2/envelope.go#L511-L520

Here's my benchmark results, comparing two ways of conversion:

```bash
╰─○ go test -v -run=none -bench=. -benchmem=true
goos: darwin
goarch: amd64
pkg: example.com/m/v2
cpu: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
BenchmarkStringToBytesUnsafe
BenchmarkStringToBytesUnsafe-12         1000000000               0.5636 ns/op          0 B/op          0 allocs/op
BenchmarkStringToBytesCasting
BenchmarkStringToBytesCasting-12        1000000000               0.2548 ns/op          0 B/op          0 allocs/op
PASS
ok      example.com/m/v2        1.448s
```

My test code:
```
package main

import (
	"testing"
	"unsafe"
)

const (
	str = "some random string"
)

func toBytes(s string) []byte {
	// unsafe.StringData is unspecified for the empty string, so we provide a strict interpretation
	if len(s) == 0 {
		return nil
	}
	// Copied from go 1.20.1 os.File.WriteString
	// https://github.com/golang/go/blob/202a1a57064127c3f19d96df57b9f9586145e21c/src/os/file.go#L246
	return unsafe.Slice(unsafe.StringData(s), len(s))
}

func toBytesRaw(s string) []byte {
	return []byte(s)
}

func BenchmarkStringToBytesUnsafe(b *testing.B) {
	for i := 0; i < b.N; i++ {
		_ = toBytes(str)
	}
}

func BenchmarkStringToBytesCasting(b *testing.B) {
	for i := 0; i < b.N; i++ {
		_ = toBytesRaw(str)
	}
}
```


### Why is this needed?

+ Kubernetes as of now is built with go 1.22, in go 1.22 type casting is faster than unsafe, regarding **only** string to bytes conversion
+ We can make string to bytes conversion faster with type casting
+ We don't need to be 'unsafe' anymore
--- end body ---

None