[clang] [llvm] Enable LLDB tests in Linux pre-merge CI (PR #94208)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

> > 2. Build system does not support Multi-config generators. You can grep for https://cmake.org/cmake/help/latest/variable/CMAKE_CFG_INTDIR.html as an example.
> 
> This simply isn't true. Xcode is a multi-config build system and we have [a bot](https://ci.swift.org/view/all/job/llvm.org/view/LLDB/job/lldb-cmake-standalone/) that ensures that doesn't break. Maybe there's something different about MSVC?

The page I linked about this deprecated variable talks about poor support in "Ninja Multi-Config" specifically, which is what I use, but implies it can be used in Xcode.

https://github.com/llvm/llvm-project/pull/94208