Swift: Use shared library for sensitive private information heuristics

[geoffw0]

This is a simple follow-up to #16446 , which added the private information heuristics from Swift to the shared sensitive data library. This PR deletes them from Swift, deferring to the shared library instead, so that we only have one copy to maintain.

There are two differences:

• terms for "ssn" and "ccn" have been added; these were discussed and tested (including an ad-hoc MRVA run for Swift) in the shared PR and I'm happy that we're now adding them to Swift.
• terms for "email" have been removed in the shared library, due to noise apparently. I've never seen that issue in Swift (and I have seen useful results from the term), so I've kept them in as an additional regexp in Swift.