Delete all Prefast tasks (#17522)
### Description
Delete all Prefast tasks because the new VS 17.7 version crashes every
time when we run the task on our CI build servers. However, we cannot
reproduce it locally. And this problem blocks us installing security
patches to our CI build machines.
Will use [CodeQL](https://codeql.github.com/) instead.
### Motivation and Context
Address some security alerts.
