[C++] Rework ReplayMerge test so it retries on failure and sets a better example.
[C++] Rework ReplayMerge test so it retries on failure and sets a better example.

EvilMcJerkface/Aeron,EvilMcJerkface/Aeron,mikeb01/Aeron,mikeb01/Aeron,EvilMcJerkface/Aeron,mikeb01/Aeron,EvilMcJerkface/Aeron,mikeb01/Aeron