test: replace common.fixturesDir in test-exception

Replace common.fixturesDir with usage of the common.fixtures module in
text-exception.js

PR-URL: nodejs/node#15964
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

test/inspector/test-exception.js

@@ -1,13 +1,13 @@
 'use strict';
 const common = require('../common');
+const fixtures = require('../common/fixtures');
 
 common.skipIfInspectorDisabled();
 
 const assert = require('assert');
 const { NodeInstance } = require('./inspector-helper.js');
-const path = require('path');
 
-const script = path.join(common.fixturesDir, 'throws_error.js');
+const script = fixtures.path('throws_error.js');
 
 async function testBreakpointOnStart(session) {
   console.log('[test]',