build(docs-infra): remove unused code (angular#44085)

This import was not being used and so it is redundant and can be removed.

PR Close angular#44085

Author: petebacondarwin

aio/tools/stackblitz-builder/builder.mjs

@@ -3,7 +3,6 @@ import path from 'canonical-path';
 import fs from 'fs-extra';
 import {globbySync} from 'globby';
 import jsdom from 'jsdom';
-import json5 from 'json5';
 import {fileURLToPath} from 'url';
 
 import regionExtractor from '../transforms/examples-package/services/region-parser.js';