Revert "Added data source google kms secret asymmetric"

[melinath]

Reverts #4609. The tests are failing in CI because default credentials aren't available. https://ci-oss.hashicorp.engineering/project.html?projectId=GoogleCloud&testNameId=-1291169185712475134&tab=testDetails

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 6 files changed, 470 deletions(-))
Terraform Beta: Diff ( 6 files changed, 470 deletions(-))
TF Conversion: Diff ( 1 file changed, 22 deletions(-))

[modular-magician]

I have triggered VCR tests based on this PR's diffs. See the results here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=180200"

[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
```