test: use common/fixtures module in hash-seed test

Replace `common.fixturesDir` with `fixtures.path()` usage in
test/pummel/test-hash-seed.js.
PR-URL: #16823
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Javier Blanco

test/pummel/test-hash-seed.js

@@ -1,20 +1,20 @@
 'use strict';
 
+// Check that spawn child doesn't create duplicated entries
+require('../common');
 constREPETITIONS=2;
-
 constassert=require('assert');
-constcommon=require('../common');
-constcp=require('child_process');
-constpath=require('path');
-consttargetScript=path.resolve(common.fixturesDir,'guess-hash-seed.js');
+constfixtures=require('../common/fixtures');
+const{ spawnSync }=require('child_process');
+consttargetScript=fixtures.path('guess-hash-seed.js');
 constseeds=[];
 
 for(leti=0;i<REPETITIONS;++i){
-constseed=cp.spawnSync(process.execPath,[targetScript],
-{encoding: 'utf8'}).stdout.trim();
+constseed=spawnSync(process.execPath,[targetScript],{
+encoding: 'utf8'
+}).stdout.trim();
 seeds.push(seed);
 }
 
 console.log(`Seeds: ${seeds}`);
-consthasDuplicates=(newSet(seeds)).size!==seeds.length;
-assert.strictEqual(hasDuplicates,false);
+assert.strictEqual(newSet(seeds).size,seeds.length);