[C] Update SystemTest for testing subscription going out of scope.
[C] Update SystemTest for testing subscription going out of scope.

real-logic/Aeron,mikeb01/Aeron,mikeb01/Aeron,EvilMcJerkface/Aeron,mikeb01/Aeron,EvilMcJerkface/Aeron,real-logic/Aeron,mikeb01/Aeron,EvilMcJerkface/Aeron,EvilMcJerkface/Aeron,real-logic/Aeron,real-logic/Aeron