Skip TestAccWorkstationsWorkstationConfig_workstationConfigEncryptionKeyExample

[modular-magician]

This test takes ~50 minutes to run, and it is running on every gcbrun before we can report the test failures for a PR.

Skipping it for now while we work out the issue, as it appears it might not be a quick fix: hashicorp/terraform-provider-google#13923

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Derived from GoogleCloudPlatform/magic-modules#7415