[lld] [llvm] DTLTO Cache optimization - rebased (PR #203971)

[Katya Romanova via llvm-commits]

romanova-ekaterina wrote:

Teresa, with the latest commit, I have only updated the failing Linux test that has been added shortly after I posted a PR. 

I will be away on vacation in the remote wilderness with zero internet access, but I will address your comment as soon as I return.

https://github.com/llvm/llvm-project/pull/203971