ci: address macos-latest test flakes (#4310)

* sdk/opa_test: increase max delta

6ms was arbitrary, and so is 10ms.

When GHA switched the macos-latest version, we've started seeing
test flakiness here.

30ms (20ms+10ms) are still waaaay below the 1s that the test_plugin
attempts need to shut down.

* test/e2e/certrefresh: double wait time for macos runner

Signed-off-by: Stephan Renatus <stephan.renatus@gmail.com>

sdk/opa_test.go

@@ -483,7 +483,7 @@ func TestStopWithDeadline(t *testing.T) {
 
 	dur := time.Since(before)
 	diff := dur - timeout
-	maxDelta := 6 * time.Millisecond
+	maxDelta := 10 * time.Millisecond
 	if diff > maxDelta || diff < -maxDelta {
 		t.Errorf("expected shutdown to have %v grace period, measured shutdown in %v (max delta %v)", timeout, dur, maxDelta)
 	}

test/e2e/certrefresh/certrefresh_test.go

@@ -94,6 +94,7 @@ func TestMain(m *testing.M) {
 }
 
 func TestCertificateRotation(t *testing.T) {
+	wait := 20 * time.Millisecond // file reload happens every millisecond
 
 	// before rotation
 	cert := getCert(t)
@@ -103,7 +104,7 @@ func TestCertificateRotation(t *testing.T) {
 
 	// replace file on disk
 	replaceCerts(t, certFile1, certKeyFile1)
-	time.Sleep(10 * time.Millisecond) // file reload happens every millisecond
+	time.Sleep(wait)
 
 	// after rotation
 	cert = getCert(t)
@@ -113,7 +114,7 @@ func TestCertificateRotation(t *testing.T) {
 
 	// replace file with nothing
 	replaceCerts(t, os.DevNull, os.DevNull)
-	time.Sleep(10 * time.Millisecond)
+	time.Sleep(wait)
 
 	// second cert still used
 	cert = getCert(t)
@@ -123,7 +124,7 @@ func TestCertificateRotation(t *testing.T) {
 
 	// go back to first cert
 	replaceCerts(t, certFile0, certKeyFile0)
-	time.Sleep(10 * time.Millisecond)
+	time.Sleep(wait)
 	cert = getCert(t)
 	if exp, act := serial0, string(cert.SerialNumber.String()); exp != act {
 		t.Fatalf("expected signature %s, got %s", exp, act)