Python: close the RedisContextProvider index connection when the provider owns it

[Manohar Paturi (ManoharPaturi)]

Motivation & Context

A provider built from only a redis_url creates an index that owns a connection pool, but the context manager exit was a no-op and there was no aclose, so the pool was never released. RedisHistoryProvider in the same package already models the right rule: close what you own, leave borrowed clients alone.

Description & Review Guide

• What are the major changes? The provider remembers whether it built the index, gains an aclose that closes the index client in that case, and the context manager exit calls it.
• What is the impact of these changes? Providers constructed from a URL now release their connections on exit. Providers receiving an injected index change nothing, which keeps callers who share a client across providers working.
• What do you want reviewers to focus on? The ownership flag mirrors _owns_client in the history provider, and the test exercises both ownership modes against the same connection.

Related Issue

Fixes #9509

AI Assistance

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