Move "Work-around for GHC 9.4 bug in ExpWithClashCF"

[leonschoorl]

Moves the workaround added in c1ef28f36fbfed5b23de04aa43cf585a8bb83377 from Exp.hs to ExpWithGhcCF.hs

When I updated the CI image from 9.4.3 to 9.4.6 the ExpWithGhcCF test started to fail on the 9.4.6 nightly test with

    Other error:
    panic! (the 'impossible' happened)
      GHC version 9.4.6:
        refineFromInScope

I've done some testing and I've found:

Using ghc <= 9.4.4:

The -fno-specialise workaround isn't need at all

Using ghc 9.4.5 and 9.4.6:

It needs the -fno-specialise workaround in ExpWithGhcCF, not in Exp. Otherwise the ExpWithGhcCF test fails, not the ExpWithClashCF like mentioned in the original commit msg.

Still TODO:

• [ ] Write a changelog entry (see changelog/README.md)
• [ ] Check copyright notices are up to date in edited files

[leonschoorl]

FYI ghc-9.4.7 still hits the same bug without the workaround