chore: code clean up for samples are migrated to python-docs-samples (#400)

* feat: code clean

Manually written code samples are migrated to GoogleCloudPlatform/python-docs-samples

For more detail, please refer to b/257073450

* Update and rename CONTRIBUTING.md to README.md

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* Update README.md

* Rename samples/README.md to samples/snippets/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: msampathkumar

samples/snippets/README.md

@@ -0,0 +1,4 @@
+Samples migrated
+================
+
+New location: https://github.com/GoogleCloudPlatform/python-docs-samples/tree/main/error_reporting