Switch test environment to a paid plan and re-enable pod-based index tests

[neon-sunset]

It appears that pod-based index tests have stopped working with the free tier used by the test environment.

This could be addressed either by Pinecone granting free credits and plan to support our library or me paying for that environment instead.

Preferably the former option is used. I did reach out to Pinecone some time ago in response to their community outreach email regarding supporting this library, but they are yet to respond. Perhaps I need to try again.