IGNITE-26495 .NET: Fix TestReadOnlyTxSeesOldDataAfterUpdate flakiness

[ptupitsyn]

No description provided.

[Copilot]

Pull Request Overview

This PR fixes the flakiness in the TestReadOnlyTxSeesOldDataAfterUpdate test by implementing a workaround for causality issues. The main change involves using a single-node connection instead of the default round-robin connection strategy to avoid observable timestamp issues with implicit client read-only transactions.

Key changes:

• Added a workaround to use single-node connection configuration
• Replaced shared client instance with local client instance using the modified configuration
• Updated all database operations to use the new local client and record view

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}