emacs-irony: Remove server directory

This contains the build files and is not needed for irony-server.
Previously, the wrong directory was removed, adding elpa/ gets thje
correct one.

pkgs/top-level/emacs-packages.nix

@@ -312,7 +312,7 @@ let
     postInstall = ''
       mkdir -p $out
       mv $out/share/emacs/site-lisp/elpa/*/server/bin $out
-      rm -rf $out/share/emacs/site-lisp/*/server
+      rm -rf $out/share/emacs/site-lisp/elpa/*/server
     '';
     preCheck = ''
       cd source/server