python: Fix --with-brewed-tk if that was installed --with-x11

Closes #19099
python: Remove outdated fix

Since 2.7.5 the `python-config --ldflags` is not fixed but Python does
not use the Makefile any longer for this. We fix this now in our
`sitecustomize.py`.
python: Use PythonInstalled#binary

This simplyfies the formula a bit.
Also rearrange the line to be more logically grouped. Hopefully.