Stop running shrinking gcs & simplify GC logic.

Shrinking GCs dump the JITted code, which leads to redundant recompilations, lowers performance, and makes profiling JS more difficult.
They may still happen if the runtime is at risk of OOM.

source/ps/Replay.cpp

@@ -197,7 +197,7 @@ void CReplayPlayer::Replay(const bool serializationtest, const int rejointesttur
 	g_ProfileViewer.AddRootTable(g_ScriptStatsTable);
 
 	const int contextSize = 384 * 1024 * 1024;
-	const int heapGrowthBytesGCTrigger = 20 * 1024 * 1024;
+	const int heapGrowthBytesGCTrigger = 12 * 1024 * 1024;
 	g_ScriptContext = ScriptContext::CreateContext(contextSize, heapGrowthBytesGCTrigger);
 
 	std::vector<SimulationCommand> commands;