test: remove third argument from call to assert.strictEqual()

Remove the message argument from call to assert.strictEqual so
that the AssertionError will report the value of er.code, and add
a comment with the message.

PR-URL: #19659
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

test/parallel/test-http-destroyed-socket-write2.js

@@ -62,12 +62,13 @@ server.listen(0, function() {
         break;
 
       default:
+        // Write to a torn down client should RESET or ABORT
         assert.strictEqual(er.code,
-                           'ECONNRESET',
-                           'Write to a torn down client should RESET or ABORT');
+                           'ECONNRESET');
         break;
     }
 
+
     assert.strictEqual(req.output.length, 0);
     assert.strictEqual(req.outputEncodings.length, 0);
     server.close();