test: fix flaky test-https-client-get-url

Fixed test-https-client-get-url by waiting on HTTPS GET requests
to finish before closing the server.
PR-URL: #12876Fixes: #12873
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

Author: Sebastian Plesciuc

test/parallel/test-https-client-get-url.js

@@ -41,18 +41,21 @@ const options = {
 cert: fs.readFileSync(`${common.fixturesDir}/keys/agent1-cert.pem`)
 };
 
-constserver=https.createServer(options,common.mustCall(function(req,res){
+constserver=https.createServer(options,common.mustCall((req,res)=>{
 assert.strictEqual('GET',req.method);
 assert.strictEqual('/foo?bar',req.url);
 res.writeHead(200,{'Content-Type': 'text/plain'});
 res.write('hello\n');
 res.end();
-server.close();
 },3));
 
-server.listen(0,function(){
-constu=`https://127.0.0.1:${this.address().port}/foo?bar`;
-https.get(u);
-https.get(url.parse(u));
-https.get(newURL(u));
-});
+server.listen(0,common.mustCall(()=>{
+constu=`https://${common.localhostIPv4}:${server.address().port}/foo?bar`;
+https.get(u,common.mustCall(()=>{
+https.get(url.parse(u),common.mustCall(()=>{
+https.get(newURL(u),common.mustCall(()=>{
+server.close();
+}));
+}));
+}));
+}));