all: use Go 1.22 range-over-int

Updates #11058

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

util/ringbuffer/ringbuffer_test.go

@@ -12,7 +12,7 @@ func TestRingBuffer(t *testing.T) {
 	const numItems = 10
 	rb := New[int](numItems)
 
-	for i := 0; i < numItems-1; i++ {
+	for i := range numItems - 1 {
 		rb.Add(i)
 	}