Finishes implementation of tests for public cluster
Fixes a few issues with generating image and parts of the tests that needed a retry
Adds a bastion host to private cluster and adapts tests to go through bastion host
Fixes private cluster. Vault was not booting because consul was not able to join the cluster. This was happening because since the cluster is private, it didn't have internet access to request cluster info. This was fixed by creating a subnet that authorizes internal calls to the google api even without internet.
Validates private cluster
Future todos:
Add artifacts logs from private cluster to circle ci. This requires implementing a function on terratest that grabs the logs through a bastion host.
Future todos: