[llvm] [llvm-debuginfo-analyzer] Remove `LVScope::Children` container (PR #144750)

[Javier Lopez-Gomez via llvm-commits]

jalopezg-git wrote:

This required a minor change to `llvm::concat_iterator`; it appears in diff here, but change is tracked separately in PR https://github.com/llvm/llvm-project/pull/144744.

https://github.com/llvm/llvm-project/pull/144750