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

[Nikolas Klauser via cfe-commits]

philnik777 wrote:

FYI in the libc++ CI we've been running the LLDB tests for a few months now and I haven't seen a single unrelated failure.

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