Set the auto scale method explicitly in ImagesWin32Tests

Set it to "smooth" so the test works as a proper regression test.

Contributes to
#1790

Author: fedejeanne

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/ImagesWin32Tests.java

@@ -25,6 +25,24 @@
 @ExtendWith(WithMonitorSpecificScalingExtension.class)
 class ImagesWin32Tests {
 
+	private static final String SWT_AUTOSCALE_METHOD = "swt.autoScale.method";
+	private static String originalAutoScaleMethod;
+
+	@BeforeAll
+	static void setUpAutoScaleMethodSmooth() {
+		originalAutoScaleMethod = System.getProperty(SWT_AUTOSCALE_METHOD);
+		System.setProperty(SWT_AUTOSCALE_METHOD, "smooth");
+	}
+
+	@AfterAll
+	static void restoreAutoScaleMethod() {
+		if (originalAutoScaleMethod != null) {
+			System.setProperty(SWT_AUTOSCALE_METHOD, originalAutoScaleMethod);
+		} else {
+			System.clearProperty(SWT_AUTOSCALE_METHOD);
+		}
+	}
+
 	@Test
 	public void testImageIconTypeShouldNotChangeAfterCallingGetHandleForDifferentZoom() {
 		Image icon = Display.getDefault().getSystemImage(SWT.ICON_ERROR);