Remove aws and azure support for BigQueryConnectionConnection

[maqiuyujoyce]

Change description

A couple of reasons why we should remove the aws and azure support in BigQueryConnectionConnection:

1. There are a few output-only fields under the top-level spec.aws and spec.azure fields. We need to handle them specially.
2. There is no test coverage for the aws or the azure support, but testing it out means we need to set up accounts in both AWS and Azure. This may be expensive.

Considering that there is no urgent request about those features, and BigQueryConnectionConnection is still a v1alpha1 kind, let's remove the aws and azure fields for now and only add them after we can support thorough testing.

Tests you have done

• Run make ready-pr to ensure this PR is ready for review.

Note that an unrelated CRD actually got generated when running make ready-pr: #2339

• [N/A] Perform necessary E2E testing for changed resources.

[yuwenma]

/lgtm
/approve

Thanks for the change. Nice to see some VRD exceptions are cleared out.

[google-oss-prow]

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