Make Hadrian solely responsible for substituting `docs/users_guide/ghc_config.py.in`

Fixes #24091
Progress on #23966

Issue #24091 reports that `@ProjectVersion@` is no longer being
substituted in the GHC user's guide. I assume this is a recent issue,
but I am not sure how it's worked since
c1a3ecde; it looks like both Hadrian and
configure are trying to substitute the same `.in` file!

Now only Hadrian does. That is better anyways; already something that
issue #23966 requested.

It seems like we were missing some dependencies in Hadrian. (I really,
really hate that this is possible!) Hopefully it is fixed now.