Add shared LLM client cache clearing utilities for tests

[koxudaxi]

TL;DR

Added cache clearing functionality for LLM client singletons to improve test isolation and provide a way to reset client state.

What changed?

• Added clear_cache() methods to all LLM client implementations (Anthropic, Azure OpenAI, Google, OpenAI)
• Created a new cache.py module with a clear_all_client_caches() function that clears all client caches at once
• Exposed the cache clearing functions through appropriate __init__.py files
• Added an autouse pytest fixture in tests/e2e/conftest.py that clears client caches before and after each e2e test

How to test?

1. Import and call clear_all_client_caches() in a test or application code
2. Verify that subsequent client creation returns fresh instances
3. Run e2e tests to confirm they execute correctly with the new cache clearing fixture

Why make this change?

This change improves test isolation by ensuring that cached LLM client singletons don't persist between tests, which could lead to test interference. It also provides a way for users to explicitly reset client state when needed, such as when changing API keys or endpoints during runtime.

[koxudaxi]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add unittest for GrokClient #1467
• Implement the GrokClient #1466
• test: force httpx in Google SDK to fix VCR.py aiohttp incompatibility #1469
• Support concurrent tool call streaming with ID-based tracking #1468
• Add unittest for mirrored provider clients (AnthropicVertex) #1465
• Implement mirrored provider clients (AnthropicVertex) #1464
• Add unittest for mirrored provider clients (AnthropicBedrock) #1455
• Implement mirrored provider clients (AnthropicBedrock) #1454
• Add shared LLM client cache clearing utilities for tests #1470 👈 (View in Graphite)
• Implement mirrored provider clients (AzureOpenAI) #1439
• Add public provider property to BaseClient #1441
• Clean up VCRConfig by replacing filter_headers with sanitization hook #1461
• v2

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Status	Name	Latest Commit	Updated (UTC)
✅ Deployment successful! View logs	v2-docs	1071cdd	Oct 30 2025, 02:50 AM