Add sanity check option to run CI pipelines for external PRs

[tianleiwu]

Description

Sometime, a PR need go through many iterations due to test or build failure. The conversion history become super long after a few iterations. It is not necessary to run 22 pipelines in early stage when the PR is not ready, and we can run a few pipelines to sanity check that the PR can pass build and test in core pipelines.

Add an option to run only a few pipelines. The usage is like python tools/python/run_CIs_for_external_pr.py 54321 -s for PR 54321

Motivation and Context