Fix #6820 Update building GHC from source

[mpilgrem]

See:

• Windows: compiler: ghc-git-<commit_id>-<Hadrian_flavour> needs update #6820

• Any changes that could be relevant to users have been recorded in ChangeLog.md.

• The documentation has been updated, if necessary

Please also shortly describe how you tested your change. Bonus points for added tests! Tested locally on Windows 11 and Ubuntu (via WSL), with ghc-git-02150b65487cb675480ed8697c956f5b69190882-quick (that is tag ghc-9.14.1-rc1).

That version of Hadrian needed the override snapshot:

snapshot: lts-24.11 # GHC 9.10.2

packages:
- Cabal-3.14.0.0
- Cabal-syntax-3.14.0.0
- directory-1.3.9.0
- file-io-0.1.4
- filepath-1.4.300.2
- process-1.6.25.0
- unix-2.8.5.1
- Win32-2.14.1.0 # Hadrian fails to include this
- time-1.12.2 # Hadrian fails to include this

[BestYeen]

The build errors in testing read "unexpected EOF while reading" when making HTTP requests to Hackage -- considering when they occurred, maybe they had to do with the Cloudflare outage somehow and could be restarted.

[BestYeen]

MacOS latest failed with a timeout on https://hackage.haskell.org/package/half-0.3.3.tar.gz, but that works for me manually currently.

[mpilgrem]

@BestYeen, thanks. Reached 'all green', in the end.