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/example-zipper/exampleZipper.js

@@ -112,6 +112,7 @@ class ExampleZipper {
       '!**/npm-debug.log',
       '!**/example-config.json',
       '!**/wallaby.js',
+      '!e2e/protractor-puppeteer.conf.js',
       // AOT related files
       '!**/aot/**/*.*',
       '!**/*-aot.*'