[llvm] [BOLT] Allow pass-through blocks in YAMLProfileReader (PR #91828)

[Maksim Panchenko via llvm-commits]

maksfb wrote:

> > Is it possible that we remove more blocks in the chain? E.g. A -> [ B -> C -> ] D?
> 
> Yes. Neither DataReader nor YAMLProfileReader will recognize that.

It shouldn't matter for the `DataReader` with new profiles.

https://github.com/llvm/llvm-project/pull/91828