JSON test files generated by the agent test runner were missing trailing newlines, causing the pre-commit end-of-file-fixer hook to fail. Added an explicit newline write on serialization.
Change-Id: Idaffc4f2c23fa213f595ddef2188b0050aeb431d
Generated test JSON files for parallel_functions and pydantic_argument samples to verify their behavior.
Also fixed a test replay issue by ignoring timestamps in state (in agent_test_runner.py) to prevent false failures due to dynamic data.
Note: Some sample agents could not have tests generated successfully due to:
1. agent_tool_with_grounding_metadata: Fails on replay because AgentTool hides sub-agent events, causing mock LLM to get out of sync.
2. hello_world_stream_fc_args: Fails on rebuild because streaming function calls are not supported in the Unary API used by the test recorder.
3. output_schema_with_tools: Has external dependencies (Wikipedia/Google Search), making it unsuitable for automated regression tests without proper mocking.
Change-Id: I69df7daf49d175905dcbd85cf70914e460717915