all: cleanup unused code, part 1 (#10661)

Run `staticcheck` with `U1000` to find unused code. This cleans up about
a half of it. I'll do the other half separately to keep PRs manageable.

Updates #cleanup

Signed-off-by: Andrew Lytvynov <awly@tailscale.com>

tstest/integration/vms/derive_bindhost_test.go

@@ -4,7 +4,6 @@
 package vms
 
 import (
-	"io"
 	"net/netip"
 	"runtime"
 	"testing"
@@ -43,9 +42,3 @@ func TestDeriveBindhost(t *testing.T) {
 	}
 	t.Log(deriveBindhost(t))
 }
-
-type nopWriteCloser struct {
-	io.Writer
-}
-
-func (nwc nopWriteCloser) Close() error { return nil }

tstest/integration/vms/vms_steps_test.go

@@ -19,8 +19,6 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
-const timeout = 15 * time.Second
-
 func retry(t *testing.T, fn func() error) {
 	t.Helper()
 	const tries = 3