test: simplify for loop in test-buffer-zero-fill-cli.js

PR-URL: #26799
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Signed-off-by: Beth Griggs <Bethany.Griggs@uk.ibm.com>

test/parallel/test-buffer-zero-fill-cli.js

@@ -9,8 +9,8 @@ const SlowBuffer = require('buffer').SlowBuffer;
 const assert = require('assert');
 
 function isZeroFilled(buf) {
- for (let n = 0; n < buf.length; n++)
- if (buf[n] > 0) return false;
+ for (const n of buf)
+ if (n > 0) return false;
  return true;
 }