Fix gc/arguments/TestNewRatioFlag.java expectedNewSize calculation

The test was started with "-XX:+CreateCoredumpOnCrash -XX:+UseParallelGC -XX:+UseNUMA -XX:-UseCompressedOops"

The test and its child process' stack traces:

----------System.err:(22/1244)----------
 stdout: [];
 stderr: [Exception in thread "main" java.lang.RuntimeException: Expected young gen size is: 9961472, but observed new size is: 9437184
at gc.arguments.TestNewRatioFlag$NewRatioVerifier.verifyPSNewRatio(TestNewRatioFlag.java:156)
at gc.arguments.TestNewRatioFlag$NewRatioVerifier.main(TestNewRatioFlag.java:106)
]
 exitValue = 1

java.lang.RuntimeException: Expected to get exit value of [0]

at jdk.test.lib.process.OutputAnalyzer.shouldHaveExitValue(OutputAnalyzer.java:474)
at gc.arguments.TestNewRatioFlag.testNewRatio(TestNewRatioFlag.java:88)
at gc.arguments.TestNewRatioFlag.main(TestNewRatioFlag.java:60)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:298)
at java.base/java.lang.Thread.run(Thread.java:831)