test: remove unnecessary Buffer import

Removed require('buffer') from

- test/disabled/test-sendfd.js
- test/internet/test-dgram-broadcast-multi-process.js
- test/pummel/test-https-no-reader.js

PR-URL: #13860
Refs: #13836
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Alexey Orlenko <eaglexrlnk@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>

test/disabled/test-sendfd.js

@@ -50,7 +50,6 @@
 const common = require('../common');
 const assert = require('assert');
 
-const buffer = require('buffer');
 const child_process = require('child_process');
 const fs = require('fs');
 const net = require('net');
@@ -112,7 +111,7 @@ var srv = net.createServer(function(s) {
   var str = JSON.stringify(DATA) + '\n';
 
   DATA.ord = DATA.ord + 1;
-  var buf = buffer.Buffer.allocUnsafe(str.length);
+  var buf = Buffer.allocUnsafe(str.length);
   buf.write(JSON.stringify(DATA) + '\n', 'utf8');
 
   s.write(str, 'utf8', pipeFDs[1]);

test/internet/test-dgram-broadcast-multi-process.js

@@ -25,7 +25,6 @@ const assert = require('assert');
 const dgram = require('dgram');
 const util = require('util');
 const networkInterfaces = require('os').networkInterfaces();
-const Buffer = require('buffer').Buffer;
 const fork = require('child_process').fork;
 const LOCAL_BROADCAST_HOST = '255.255.255.255';
 const TIMEOUT = common.platformTimeout(5000);

test/pummel/test-https-no-reader.js

@@ -29,7 +29,6 @@ if (!common.hasCrypto) {
 }
 const https = require('https');
 
-const Buffer = require('buffer').Buffer;
 const fs = require('fs');
 const path = require('path');