CRIU Pingperf adds test loop for SharedClasses validation

[LongyuZhang]

Based on Issue https://github.com/eclipse-openj9/openj9/issues/20012, OpenLiberty utilizes the established shared classes for multiple servers, so we need to increase Pingperf test to loop this test several times inside the container to validate the built shared classes. FYI @tajila @llxia