Pull request: all: fix windows tempdir

Merge in DNS/adguard-home from try-fixing-windows-tests to master

Squashed commit of the following:

commit 25a43db5d53f24b98921efa21d8d2f231992e761
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Mar 26 21:19:00 2021 +0300

    all: fix windows tempdir

internal/util/autohosts_test.go

@@ -21,7 +21,7 @@ func TestMain(m *testing.M) {
 func prepareTestFile(t *testing.T) (f *os.File) {
 	t.Helper()
 
-	dir := aghtest.PrepareTestDir(t)
+	dir := t.TempDir()
 
 	f, err := ioutil.TempFile(dir, "")
 	require.Nil(t, err)