Cleanup tempfiles (#3986)

* cleanup tempfiles for auto_test
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>

* cleanup tempfiles for metrics_test
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>

test/auto_test.go

@@ -16,6 +16,7 @@ func TestAuto(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer os.RemoveAll(tmpdir)
 
 	corefile := `org:0 {
 		auto {
@@ -74,6 +75,7 @@ func TestAutoNonExistentZone(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer os.RemoveAll(tmpdir)
 
 	corefile := `.:0 {
 		auto {
@@ -112,6 +114,7 @@ func TestAutoAXFR(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer os.RemoveAll(tmpdir)
 
 	corefile := `org:0 {
 		auto {

test/metrics_test.go

@@ -73,6 +73,7 @@ func TestMetricsAuto(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer os.RemoveAll(tmpdir)
 
 	corefile := `org:0 {
 		auto {