fix: agent generate config err

[simonwei97]

Code Update

I modified both _get_completion_inputs and generate_content_async functions, the associate file is src/google/adk/models/lite_llm.py.

Test Case

unittests

• reomve useless lib json.
• remove duplicate case test_generate_content_async (same code L430-L507)
• add test_get_completion_inputs_generation_params for func _get_completion_inputs

Fixes: #1302

[hangfei]

@genquan9 Could you help review this change?

[genquan9]

Thanks a lot for the help!
The change is great in general!
I only added minor comments.
Could you resolve the comments?

[simonwei97]

Thanks a lot for the help! The change is great in general! I only added minor comments. Could you resolve the comments?

@genquan9 Thanks for your suggestion. I fixed the problem mentioned in above comments.

[genquan9]

Thanks a lot!