test: removed string from assert message arg

PR-URL: nodejs/node#15954
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

test/parallel/test-zlib-from-gzip.js

@@ -45,7 +45,7 @@ const out = fs.createWriteStream(outputFile);
 inp.pipe(gunzip).pipe(out);
 out.on('close', common.mustCall(() => {
   const actual = fs.readFileSync(outputFile);
-  assert.strictEqual(actual.length, expect.length, 'length should match');
+  assert.strictEqual(actual.length, expect.length);
   for (let i = 0, l = actual.length; i < l; i++) {
     assert.strictEqual(actual[i], expect[i], `byte[${i}]`);
   }