SizeEstimator class not always properly initialized in tests.

The SizeEstimator class reads some system properties when it is initialized. Some tests override these system properties in order to force the SizeEstimator class to produce the same results on all platforms. However there are multiple places where the SizeEstimator class is either not re-initialized after system properties have been changed or system properties are not correctly set.

This causes test failures when using OpenJ9 compiled in large heap mode. This build of OpenJ9 does not use compressed references which affects the settings that SizeEstimator is originally initialized with.

I have a PR that fixes this and will submit it shortly.