Policy API: Use "General Availability" (GA) Release URL

[rlxdev]

🗣 Description

Changed the URL for the Policy API from

https://cloudidentity.googleapis.com/v1beta1/policies (beta release)
to
https://cloudidentity.googleapis.com/v1/policies

Closes #518

🧪 Testing

Run ScubaGoggles with the new URL. Works as expected, with results returned by the Policy API.

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