CloseRace.java#id0 fails transiently on libgraal

The java/lang/ProcessBuilder/CloseRace.java#id0 test fails transiently on libgraal when run with -Xcomp with:

java.lang.Error: At least one child thread (Thread-2) failed to finish gracefully
        at CloseRace.main(CloseRace.java:122)
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
        at java.base/java.lang.reflect.Method.invoke(Method.java:580)
        at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
        at java.base/java.lang.Thread.run(Thread.java:1570)

Possible fixes would include:
* Disable the test under -Xcomp
* Increase the time the main thread waits for other threads to join. For example, it could be adjusted by JTREG_TIMEOUT_FACTOR (which is typically increased when running test with -Xcomp).