Reduce the number of park and unpark iterations in ParkALot

ParkALot launches a number of virtual threads and expects each thread
to park and unpark 500_000 times. The test takes a lot of time to
execute leading to timeouts in Jenkins testing.

The number of park and unpark iterations is reduced to 5_000, which is
sufficient to verify functional behaviour. Further, the reduced
iterations allow the test to pass in a reasonable time in Jenkins
testing.

vm.debug is set to false for OpenJ9. So, the vm.debug=true variant is
left unmodified.

Related: eclipse-openj9/openj9#18444

Signed-off-by: Babneet Singh <sbabneet@ca.ibm.com>

test/jdk/java/lang/Thread/virtual/stress/ParkALot.java

@@ -21,11 +21,17 @@
  * questions.
  */
 
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2023, 2023 All Rights Reserved
+ * ===========================================================================
+ */
+
 /*
  * @test
  * @summary Stress test parking and unparking
  * @requires vm.debug != true
- * @run main/othervm ParkALot 500000
+ * @run main/othervm ParkALot 5000
  */
 
 /*