graylog2-server: move to boneyard.

The formula is for an ancient version of Graylog2 and doesn't work because
the tarball doesn't exist any more.

Closes Homebrew/homebrew#35868.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/tap_migrations.rb

@@ -56,6 +56,7 @@ TAP_MIGRATIONS = {
   "gpredict" => "homebrew/x11",
   "grace" => "homebrew/x11",
   "grads" => "homebrew/binary",
+  "graylog2-server" => "homebrew/boneyard",
   "gromacs" => "homebrew/science",
   "gsmartcontrol" => "homebrew/x11",
   "gtk-chtheme" => "homebrew/x11",