refactor: wrap execSync with encoding: utf-8 (#188)

Author: jkwlui

dataproc/system-test/quickstart.test.js

@@ -14,7 +14,9 @@
  */
 
 const {assert} = require('chai');
-const {execSync} = require('child_process');
+const cp = require('child_process');
+
+const execSync = cmd => cp.execSync(cmd, {encoding: 'utf-8'});
 
 describe('dataproc samples', () => {
   it('should run the quickstart', async () => {