Revert "Issue #2156401 by alexpott, moshe weitzman, tedbow, dawehner, greg.1.anderson, phenaproxima, chris.smith, heddn, balsama, xjm, Mile23, izus, Manuel Garcia, sun, pwolanin, Berdir: Write install_profile value to configuration and only to settings.php if it is writeable"

This reverts commit 480eb82c.