Complete AsyncClassifier Tests

## Description
The AsyncClassifier functionality needs more comprehensive test coverage. Currently, some async tests are being skipped or only minimal tests are implemented.

## Tasks
- [ ] Add thorough test coverage for all AsyncClassifier methods
- [ ] Implement tests for edge cases in async operations
- [ ] Test async error handling and recovery
- [ ] Test concurrency limits and behavior
- [ ] Ensure compatibility with different event loops and async frameworks
- [ ] Add tests for async batch operations with different job counts

## Expected Result
A comprehensive test suite for AsyncClassifier that ensures all functionality works correctly in async contexts and gives confidence that async code paths are robust.

## Why is this important?
Asynchronous operation is a key feature of the library, and proper testing ensures it works correctly in production environments.

## Difficulty
Medium - requires understanding of async testing principles with pytest-asyncio