Simplify "Preparing metadata" logging
Simplify "Preparing metadata" logging

Do not mention wheel, as this code path is also used
in legacy editable mode with isolation, where
no wheel is involved.

This also aligns with the new log entry for setup.py egg-info
which says "Preparing metadata (setup.py)".

sbidoul/pip,pypa/pip,pypa/pip,pradyunsg/pip,pfmoore/pip,sbidoul/pip,pradyunsg/pip,pfmoore/pip