Revert "Add CDN load balancer with Cloud Storage buckets as backend"

[slevenick]

Reverts #5575

This test doesn't pass due to external providers. Removing until it can pass

[modular-magician]

Oops! It looks like no changelog entry is attached to this PR. Please include a release note block in the PR body, as described in https://github.com/GoogleCloudPlatform/magic-modules/blob/master/.ci/RELEASE_NOTES_GUIDE.md:

```release-note:TYPE
Release note
```

[c2thorn]

Looking into it, it probably fails because we don't support hashicorp/terraform-provider-google#10202

looks like it was primarily made for cloud.google.com samples, and generated here: https://github.com/terraform-google-modules/terraform-docs-samples/tree/master/external_cnd_lb_with_backend_bucket

This is a similar situation as #5248, where we just added the skip_test: true. @slevenick would you be okay with just skipping tests for this example until we support external providers?

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 145 deletions(-))
Terraform Beta: Diff ( 2 files changed, 310 deletions(-))
TF Validator: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))
TF OiCS: Diff ( 4 files changed, 236 deletions(-))

[c2thorn]

Agreed to revert after discussion.