build(docs-infra): use puppeteer to get a browser for docs examples tests (#35381)

In #35049, integration and AIO tests were changed to use the browser
provided by `puppeteer` in tests. This commit switches the docs examples
tests to use the same setup.

IMPLEMENTATION NOTE:
The examples are used to create ZIP archives that docs users can
download to experiment with. Since we want the downloaded projects to
resemble an `@angular/cli` generated project, we do not want to affect
the project's Protractor configuration in order to use `puppeteer`.

To achieve this, a second Protractor configuration is created (which is
ignored when creating the ZIP archives) that extends the original one
and passes the approperiate arguments to use the browser provided by
`puppeteer`. This new configuration (`protractor-puppeteer.conf.js`) is
used when running the docs examples tests (on CI or locally during
development).

PR Close #35381

aio/tools/examples/shared/protractor.config.js

@@ -20,7 +20,12 @@ exports.config = {
 
   // Capabilities to be passed to the webdriver instance.
   capabilities: {
-    'browserName': 'chrome',
+    browserName: 'chrome',
+    chromeOptions: {
+      binary: require('puppeteer').executablePath(),
+      // See /integration/README.md#browser-tests for more info on these args
+      args: ['--no-sandbox', '--headless', '--disable-gpu', '--disable-dev-shm-usage', '--hide-scrollbars', '--mute-audio'],
+    },
   },
 
   // Framework to use. Jasmine is recommended.