8287663: Add a regression test for JDK-8287073

Reviewed-by: iklam

src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemFactory.java

@@ -86,7 +86,10 @@ public class CgroupSubsystemFactory {
         } catch (IOException | UncheckedIOException e) {
             return null;
         }
+        return create(optResult);
+    }
 
+    public static CgroupMetrics create(Optional<CgroupTypeResult> optResult) {
         if (optResult.isEmpty()) {
             return null;
         }