Remove Unsafe Browser bookmarks from the default system-wide profile skeleton too (Closes #7594).

Commit dadb276ff drops this operation, and instead only removes the bookmarks
from the already created profile in /home/clearnet. This is incorrect (and
apparently untested): when no bookmarks exist on Firefox startup, it imports
the default ones from the system-wide profile skeleton.

So, here we remove bookmarks from both places.

config/chroot_local-includes/usr/local/sbin/unsafe-browser

@@ -186,6 +186,7 @@ EOF
         ${CLEARNET_PROFILE}/user.js
 
     # Remove all bookmarks
+    rm -f ${CHROOT}/etc/iceweasel/profile/bookmarks.html
     rm -f ${CLEARNET_PROFILE}/bookmarks.html
     rm -f ${CLEARNET_PROFILE}/places.sqlite
 }