withShorterPathForNewBuildStore needs the windows tempDir hack

[gbaz]

In particular

cabal/cabal-testsuite/src/Test/Cabal/Prelude.hs

Line 1000 in 78fbe09

withShorterPathForNewBuildStore :: (FilePath -> IO a) -> IO a

should make use of withTestDir

cabal/cabal-install/tests/UnitTests/TempTestDir.hs

Line 26 in 00a2351

withTestDir :: Verbosity -> String -> (FilePath -> IO a) -> IO a

so that we don't get sporadic windows failures with removeDirectoryRecursive throwing on permissions errors.

[Mikolaj]

Possible example of such a failure: https://ci.appveyor.com/project/23Skidoo/cabal/builds/40384463