test: use conventional argument order in assertion

PR-URL: #40591
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Voltrex <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: tniessen

test/parallel/test-buffer-fill.js

@@ -315,7 +315,7 @@ Buffer.alloc(8, '');
 
   buf.fill('h');
   for (let i = 0; i < buf.length; i++)
-    assert.strictEqual('h'.charCodeAt(0), buf[i]);
+    assert.strictEqual(buf[i], 'h'.charCodeAt(0));
 
   buf.fill(0);
   for (let i = 0; i < buf.length; i++)