### Description
<!-- Describe your changes. -->
build.py sets a few parallelization parameters when building. Using
msbuild directly lacks those.
7a5860e490/tools/ci_build/build.py (L1665-L1669)
Changed to use build.py. If there's a concern with that we _could_ set
the parameters in the yaml, but that will be uglier due to duplicating
logic in multiple places.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
