[PLT-0] Fix flaky test_request_labeling_service_moe_project

[lb-pno]

Description

Remove unused live_chat_evaluation_project dependency from live_chat_evaluation_project_with_batch fixture and add retry logic for transient ER_LOCK_DEADLOCK errors. The redundant dependency triggered an extra create_model_evaluation_project call that increased deadlock probability.

Fixes # (issue)

Type of change

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Note

Low Risk
Test-only fixture changes add retry/backoff around project creation, which could slightly increase test runtime but doesn’t affect production code paths.

Overview
Reduces flakiness in test_request_labeling_service_moe_project setup by removing the unused live_chat_evaluation_project dependency from live_chat_evaluation_project_with_batch, avoiding an extra create_model_evaluation_project call.

Adds a small retry-with-sleep loop around client.create_model_evaluation_project to handle transient ER_LOCK_DEADLOCK errors when tests run in parallel.

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