Use a warmup instead

Seems more stable

Bench.cpp

@@ -236,9 +236,7 @@ void benchConflictSet() {
 
   bench.batch(1);
 
-  cs.setOldestVersion(version - kMvccWindow);
-
-  bench.minEpochIterations(1000000);
+  bench.warmup(10000);
 
   {
     bench.run("monotonic increasing point writes", [&]() {