[lld] [test] Fixes #120514 (PR #125450)

[Pengying Xu via llvm-commits]

Colibrow wrote:

https://github.com/llvm/llvm-project/blob/fe8b323f598393d5a7cf468865c4f60d39cb0718/llvm/lib/Support/BalancedPartitioning.cpp#L308-L310
Maybe I am wrong. Splitting the nodes using std::nth_element causes a slight difference because this API doesn't guarantee the order of initialization. In my opinion, it shouldn't affect the final order, but it does. When I switched to `llvm::sort`, it seems to match. 

https://github.com/llvm/llvm-project/pull/125450