Switch class loading logic in blackBoxWithJava tests

BoxWithJava tests now by default are loaded with the classloader which has
test's classpath in itself, as in the former ClassPathInTheSameClassLoaderTest

compiler/testData/codegen/boxWithJava/visibility/protectedStatic/simpleClass.java

@@ -0,0 +1,8 @@
+public class simpleClass {
+    protected static class Inner {
+        public Inner() {}
+        public String foo() {
+            return "OK";
+        }
+    }
+}