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

.circleci/config.yml

@@ -446,13 +446,13 @@ jobs:
         type: boolean
         default: false
     executor:
-      # Needed because the example e2e tests depend on Chrome.
-      name: browsers-executor
+      name: default-executor
       resource_class: xlarge
     parallelism: 5
     steps:
       - custom_attach_workspace
       - init_environment
+      - install_chrome_libs
         # Install aio
       - run: yarn --cwd aio install --frozen-lockfile --non-interactive
       - when: