RFR (T) 8223190: Test gc/arguments/TestShrinkHeapInSteps.java breaks with change for JDK-8074355

[coleen.phillimore at oracle.com]

Summary: Remove too strict assert.

See bug for details.  David didn't like this assert.

Built and tested locally.

open webrev at http://cr.openjdk.java.net/~coleenp/2019/8223190.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8223190

Thanks to Harold for the failure alert!
Coleen