Fix next-pylint issue

[dargilco]

Fix for GitHub issue "azure-ai-inference needs linting updates for pylint version 3.2.7" (#39270)

Running

>pip install "tox<5"
>tox run -e next-pylint -c ../../../eng/tox/tox.ini --root .

Resulted in this error:

************* Module azure.ai.inference.models._patch
azure\ai\inference\models\_patch.py:506: [C4763(do-not-import-asyncio), AsyncStreamingChatCompletions.__exit__] Do not import the asyncio package directly in your library

The fix is to make sure the async iterator class has the proper async exit method (__aexit__). I also made sure the "with context" pattern works with the streaming response object, by updating some of the streaming tests.

[azure-sdk]

API change check

APIView has identified API level changes in this PR and created following API reviews.

azure-ai-inference