themes: Remove Raleigh

themes: Remove Raleigh

It has been extremely broken since the move to CSS gadgets/nodes, so
clearly no one is depending on it; nor does anyone seem to want to
resurrect it, and writing a Raleigh-inspired theme from scratch would be
faster if they did. So let's drop the dead weight from the build and lib

Now that we don't have Raleigh, the defaultvalue test has to be changed
to set Adwaita before checking the default values of style properties -
some of which Adwaita overrides in its CSS, meaning those would fail.
Not that it passed before anyway! But it does now after my other commit.

Note that I leave the last reference in gtk-zip.sh.in alone since that
hasn't been touched in 8 years and probably has plenty other problems...

Close https://gitlab.gnome.org/GNOME/gtk/issues/1187