[SPE-4470] Default to env var when api_key param is not passed in Python SDK

[rich-song]

Noticed that it doesn't default to env var when creating Python SDK client without api_key param but it does for Typescript SDK. What is the expected behavior?

_SPE-4470

[simplesagar]

Hi @rhjsong i think you're right. I don’t have a good reason for the default. We’ll investigate whether we can change that. Thanks !