OpenTelemetry tracing support

[tewbo]

Pull request type

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

The YDB Python SDK does not provide built-in OpenTelemetry tracing support. There is legacy integration with OpenTracing API which uses the deprecated standard.

Issue Number: N/A

What is the new behavior?

Adds OpenTelemetry tracing support to the YDB Python SDK. When enabled via enable_tracing(), the SDK automatically creates spans for key operations:

• ydb.CreateSession — session creation
• ydb.ExecuteQuery — query execution (session and transaction level, both sync and async)
• ydb.Commit / ydb.Rollback — transaction commit and rollback
• ydb.Driver.Initialize — driver initialization

Each span includes standard attributes: db.system.name, db.namespace, server.address, server.port, ydb.session.id, ydb.node.id, ydb.tx.id.

W3C Trace Context (traceparent) is automatically propagated in gRPC metadata, enabling end-to-end distributed tracing between client and YDB server. Execute spans cover the full operation lifecycle, including streaming result iteration — not just the initial gRPC call. Errors are recorded on spans with error.type, db.response.status_code, and exception events.

Tracing is opt-in (pip install ydb[tracing] + enable_tracing()). Without it, the SDK behavior is unchanged — all tracing code paths are no-op.

Other information

• Includes unit tests for sync, async, error handling, parent-child relationships, context propagation, noop mode, and concurrent span isolation