[Dev] outdated repos

[bill-auger]

re: https://labs.parabola.nu/issues/2540

while going over the repos in pacman.conf and the wiki, i noticed
several repos that are not in the pacman.conf's - these have not
seen any attention in years - are any of these useful anymore? -
should we delete them?

REPO            LAST UPDATED
----------------------------
alarm           2018-10-08
cross           2012-01-23
gnome-unstable  2014-10-03
java            2017-02-14
kde-unstable    2014-10-03