sweet/tile38: make the default benchmark shorter

The purpose of such a high iteration count was to ensure the benchmark
reaches a steady-state with respect to the GC, but the count was way
overkill. This change reduces it.

Change-Id: I8e2f43e75e766a52347491ad37bb3835c167d717
Reviewed-on: https://go-review.googlesource.com/c/benchmarks/+/378454
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
diff --git a/sweet/benchmarks/tile38/main.go b/sweet/benchmarks/tile38/main.go
index f631724..6dcca19 100644
--- a/sweet/benchmarks/tile38/main.go
+++ b/sweet/benchmarks/tile38/main.go
@@ -313,7 +313,7 @@
 		driver.BenchmarkPID(srvCmd.Process.Pid),
 		driver.DoPerf(true),
 	}
-	iters := 60 * 50000
+	iters := 20 * 50000
 	if cfg.short {
 		iters = 1000
 	}