Refactor flake patching/recursion

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

lib/scripts/remove-host.sh

@@ -18,9 +18,8 @@ find . -type f -name "sops.yaml" | while IFS= read -r sops_file; do
   sed -i "/          - \*$host/d" "$sops_file"
 done
 
-sed -i "/$host/d" ./hosts/common/configs/system/ssh/default.nix
-sed -i "/$host = nixpkgs.lib.nixosSystem rec {/,/^[[:space:]]*};/d" flake.nix
-sed -i "/$host/d" ./README.md
+sed -i "/$host = mkNixosConfiguration/d" flake.nix
+sed -i "/`$host`/d" ./README.md
 
 rm -rf "./hosts/$host"