Update sample_create_client.py for Beta 3 API

[annelo-msft]

The sample_create_client.py feels like it fits to the shape of the original Beta 1 sample. Please consider making the following updates:

• Refer to ContainerRepository as something other than client here and here
• Since ContainerRepository isn't a client, we shouldn't be able to create an instance of it directly as we do here, unless this is a Python-specific requirement.
• In the proposed Beta3 API, we're not exposing functionality to list tags on a repository directly as we do here.
• If you'd like to illustrate the use of ContainerRepository in this sample, consider also including an illustration of ArtifactRegistry, as it is another Helper type that makes service calls.

[seankane-msft]

@annelo-msft Regarding your second point, is it impossible to create an instance of ContainerRepository directly? I haven't discovered a way to completely forbid this on the Python side.

[annelo-msft]

I'm not sure what's possible in Python for these mini-client types. Do you have an example of something similar to the .NET CosmosDatabase type in the Python Cosmos library?

If Python does allow creating an instance directly, consider not illustrating this in a sample, and instead using the getter method on the ContainerRegistryClient?

[seankane-msft]

I don't see this functionality on the cosmos python library. For now I won't show creating the client directly and refer to the get_repository method.