Revert "benchmarks: add system prompt to baseline arm so it doesn't ramble (closes #126) (#128)"

This reverts commit 37f46b8f02.

benchmarks/arms/baseline.js

@@ -1,6 +1,2 @@
-// Baseline arm: no skill, with a one-line system prompt so the model doesn't ramble.
+// Baseline arm: no skill, just the task.
-const system = 'Provide just one example for any given task, and no commentary or usage examples.';
+module.exports = ({ vars }) => [{ role: 'user', content: vars.task }];
-module.exports = ({ vars }) => [
-  { role: 'system', content: system },
-  { role: 'user', content: vars.task },
-];