{AKS} Update unit test check-in pipeline

[FumingZhang]

---

This checklist is used to make sure that common guidelines for a pull request are followed.

• Add coverage inspection in unit test check-in pipeline, error will be reported when it is lower than the preset value.
• Fix the testsdk changes introduced in PR #20601.

General Guidelines

• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

About Extension Publish

There is a pipeline to automatically build, upload and publish extension wheels.
Once your PR is merged into master branch, a new PR will be created to update src/index.json automatically.
The precondition is to put your code inside this repo and upgrade the version in the PR but do not modify src/index.json.