{AKS} Fix AKS PR check-in pipeline

[FumingZhang]

• fix trigger branch (from master to main)
• update pipeline agent/pool to 'ubuntu-latest'
• update scripts

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.

[yonzhan]

AKS

[zhoxing-ms]

@FumingZhang May I ask if this PR title need to appear in release notes as a history?

[FumingZhang]

@FumingZhang May I ask if this PR title need to appear in release notes as a history?

No, I have changed the title.