In f70fc980, while refactoring
buildInplaceUnpackedPackage and buildAndInstallUnpackedPackage, we
started logging into a file on both cases, instead of logging to a file
only for buildAndInstallUnpackedPackage.

When building a package inplace, it is much more useful to be able to
see the GHC invocation directly outside of a log file.

This is especially relevant for Cabal developers working inplace.

Fixes #9606