[lld] [lldb] [llvm] [mlir] Rename ThreadPool->DefaultThreadPool and ThreadPoolInterface->ThreadPool (NFC) (PR #83702)

[Mehdi Amini via llvm-commits]

joker-eph wrote:

> One patch ThreadPool->DefaultThreadPool (people get a build error about ThreadPool not being the name of anything, find this patch as the root cause, and rename all their ThreadPool->DefaultThreadPool)

Gotcha, thanks for elaborating, somehow my brain was slow on a Monday.
Will look into this!

https://github.com/llvm/llvm-project/pull/83702