test: remove unused variables from HTTPS tests

PR-URL: https://github.com/nodejs/node/pull/4426
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>

test/parallel/test-https-timeout-server.js

@@ -9,7 +9,6 @@ if (!common.hasCrypto) {
 var https = require('https');
 
 var net = require('net');
-var tls = require('tls');
 var fs = require('fs');
 
 var clientErrors = 0;