docs: Python EVALSHA OpenTelemetry span support

[Aryex]

Summary

Update OpenTelemetry concepts page to reflect that the Python client now traces EVALSHA (script invocation) spans.

⚠️ Attention: This PR was generated automatically. Verify that all relevant pages have been updated.

Source Commits

• 7762c4c — Python Async: Add OTel span creation for script invocation (EVALSHA) (#6350)

Changes

• Updated the "Tracing Integration" note in concepts/client-features/open-telemetry.mdx to reflect that EVALSHA is now traced in the Python client (both async and sync)
• SCAN family commands remain listed as un-instrumented across all clients
• Added note that EVALSHA tracing for Java, Node.js, Go, C#, and PHP is planned

Context

valkey-glide #6350 adds EVALSHA OpenTelemetry span creation to the Python client's _execute_script method (both async and sync). Previously, script invocations passed a hardcoded 0 span pointer to the FFI, making them invisible in traces. Now EVALSHA spans appear with full DB semantic convention attributes (db.operation.name, db.query.text, db.system.name, server.address, server.port, db.namespace). The Python client is the first GLIDE client to support this.

cc @naoki-tateyama

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This PR was generated by the automated documentation pipeline.