test: remove common.fileExists()

test-trace-event-promises.js was added to the codebase between the last
CI for nodejs#22151 and it landing.

Refs: nodejs#22151

test/parallel/test-trace-event-promises.js

@@ -33,7 +33,7 @@ if (process.argv[2] === 'child') {
   proc.once('exit', common.mustCall(() => {
     const file = path.join(tmpdir.path, 'node_trace.1.log');
 
-    assert(common.fileExists(file));
+    assert(fs.existsSync(file));
     fs.readFile(file, common.mustCall((err, data) => {
       const traces = JSON.parse(data.toString()).traceEvents
         .filter((trace) => trace.cat !== '__metadata');