[clang] [llvm] [NFC][analyzer] Remove Z3-as-constraint-manager hacks from lit test code (PR #145731)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

I showed the contents of this commit to @gamesh411 and we decided to mark the two "expected to fail" tests with XFAIL to ensure that we don't introduce new failures (he clarified that before my commit by default they were in an UNSUPPORTED state, and not a crashing/failing state).

https://github.com/llvm/llvm-project/pull/145731