Automatic creation of .directory files is one of the most
complained about things in dolphin.
These days applications are supposed to store application-specific data
within $XDG_DATA_HOME. Long-term that's the proper solution for this
issue, but for now we can at least flip the default so that we no longer
create .directory files out of the box.
A tooltip is also added as a kind of warning for the users who want to
change the setting. Ideally a proper warning should be shown using a
KMessageWidget or KMessageBox, but neither play too well with the
setting dialog workflow used by dolphin.