test: replace common.fixturesDir w/ fixtures.path

PR-URL: #15819
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-tls-connect-secure-context.js

@@ -1,12 +1,12 @@
 'use strict';
-const common = require('../common');
+require('../common');
 
 // Verify connection with explicitly created client SecureContext.
 
-const join = require('path').join;
+const fixtures = require('../common/fixtures');
 const {
   assert, connect, keys, tls
-} = require(join(common.fixturesDir, 'tls-connect'));
+} = require(fixtures.path('tls-connect'));
 
 connect({
   client: {