refactor: simpler local integration tests

[hown3d]

Description

This PR tries to simplify the process of running the integration tests on a developer machine.

• remove dependency to gsutil and creates a package for interacting with gcs buckets.
• add pattern matching for dockerfiles
  • in order to run only a portion of dockerfiles during integration testing
  • running all files can exhaust the dockerhub pull limit pretty fast
• start a local registry during integration-test script execution, if LOCAL environment variable is set.
• dockerignore to prevent rebuilding kaniko during integration test file changes

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes unit tests
• Adds integration tests if needed.

See the contribution guide for more details.

Reviewer Notes

• The code flow looks good.
• Unit tests and or integration tests added.

Release Notes

Simplify local integration tests

[imjasonh]

Thanks for this contribution! Anything that makes integration tests easier to run locally will help contributors and reviewers, so thank you so much for this. 🙏