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

[Michał Górny via llvm-commits]

mgorny wrote:

It's rather caused by doing a multilib build — in general you can't really use `CMAKE_CXX_COMPILER` outside CMake, since CMake is doing some toolchain magic on that, and you can't reproduce it right in lit. Unfortunately, I can't think of a good way of determining whether to run that, and I think actually switching to compile the library via CMake is easier — I'm already almost done, just need to wait for some free resources to start testing.

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