test/jdk/jdk/jfr/api/consumer/TestHiddenMethod uses nashorn script engine. But nashorn engine has been removed (JEP: https://openjdk.java.net/jeps/372). Port the test to avoid nashorn.

Test also fails in CI with NullPointerException:
Test: jdk/jfr/api/consumer/TestHiddenMethod.java
Platforms: ALL
Failure:
java.lang.NullPointerException
at jdk.jfr.api.consumer.TestHiddenMethod.main(TestHiddenMethod.java:66)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:832)


====== Related to Nashorn removal, the failure is in engine.eval():
           ScriptEngine engine = manager.getEngineByName("nashorn");
            engine.eval(...) <<------ Line 66, NPE