remove metadata property for version-tolerant generation

[iscai-msft]

Right now, we generate url metadata for each of our operations (see here).

This was an early attempt at getting some level of ability for users to modify the requests we make. However, with our new version tolerant approach, it's no longer necessary to have this backdoor, since we have send_request etc, giving users more control over the generated code. Additionally, having this metadata function makes it hard to customize our own operations, since you have to include this metadata on your custom operations. Thus, we want to remove metadata for our version tolerant generations, and this won't be breaking because we haven't GAd our version tolerant generator yet