all: use Go 1.22 range-over-int

Updates #11058

Change-Id: I35e7ef9b90e83cac04ca93fd964ad00ed5b48430
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

util/ringbuffer/ringbuffer.go

@@ -51,7 +51,7 @@ func (rb *RingBuffer[T]) GetAll() []T {
 	rb.mu.Lock()
 	defer rb.mu.Unlock()
 	out := make([]T, len(rb.buf))
-	for i := 0; i < len(rb.buf); i++ {
+	for i := range len(rb.buf) {
 		x := (rb.pos + i) % rb.max
 		out[i] = rb.buf[x]
 	}