LPS-47346 Use ant instead of exec for better build performance

Hi Shuyang,

It seems Brian did not like our old solution about this problem, this time I fixed it in the caller part instead of callee.

A potential risk of this solution is thead safe, since it modifies current project. However, I checked our build process, it is safe to do this since there is no Parallel task running, all tasks are executed one by one.

Any question, please let me know.

Thanks.
Tina.