Unmark as beta, skip test as privateca does not have beta endpoints

[modular-magician]

I broke the build by marking this test as beta.

Marking it as beta has some requirements that the resource itself must have a beta version for everything to work correctly. PrivateCA does not have a beta version, so this ends up breaking the build.

Skipping the test as it requires a beta-only resource

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Derived from GoogleCloudPlatform/magic-modules#5247

[github-actions]

I'm going to lock this pull request because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
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