benchmark: adjust configuration for string-decoder bench

According to #59186 this benchmark file takes 6 hours to complete a full benchmark/compare.js script (60 runs in total) and this regression tests unrealitics to do between Node.js releases. By using calibrate-n scripts I could find a better N also ajusting some bench configs. e.g: avoid dead code elimination by V8. PR-URL: #59187 Refs: #59186 Reviewed-By: Vinícius Lourenço Claro Cardoso <contact@viniciusl.com.br> Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: RafaelGSS

benchmark/string_decoder/string-decoder.js

@@ -1,11 +1,12 @@
 'use strict';
 const common = require('../common.js');
 const StringDecoder = require('string_decoder').StringDecoder;
+const assert = require('node:assert');
 
 const bench = common.createBenchmark(main, {
  encoding: ['ascii', 'utf8', 'base64-utf8', 'base64-ascii', 'utf16le'],
- inLen: [32, 128, 1024, 4096],
- chunkLen: [16, 64, 256, 1024],
+ inLen: [32, 128, 1024],
+ chunkLen: [16, 256, 1024],
  n: [25e5],
 });
 
@@ -75,10 +76,13 @@ function main({ encoding, inLen, chunkLen, n }) {
 
  const nChunks = chunks.length;
 
+ let avoidDeadCode;
  bench.start();
  for (let i = 0; i < n; ++i) {
+ avoidDeadCode = '';
  for (let j = 0; j < nChunks; ++j)
- sd.write(chunks[j]);
+ avoidDeadCode += sd.write(chunks[j]);
  }
  bench.end(n);
+ assert.ok(avoidDeadCode);
 }