[Analyzer][Z3] Test fixes for Z3 constraint manager

Summary:
Since Z3 tests have been not been running [1] some tests needed to be
updated. I also added a regression test for [1].

[1] https://reviews.llvm.org/D47722

Reviewers: george.karpenkov, NoQ, ddcc

Reviewed By: george.karpenkov

Subscribers: mikhail.ramalho, dcoughlin, xazax.hun, szepet, zzheng, a.sidorin, cfe-commits

Differential Revision: https://reviews.llvm.org/D47726

llvm-svn: 334067