leetcode: avoid duplicate fzf-lua

Fixes the following evaluation warning:

> evaluation warning: mnw: both startAttrs."fzf-lua" and optAttrs."fzf-lua" are defined and not null
>                     This will cause the plugin to be installed under /opt and /start.

modules/plugins/utility/leetcode-nvim/config.nix

@@ -11,7 +11,6 @@ in {
     vim = {
       startPlugins = [
         "plenary-nvim"
-        "fzf-lua"
         "nui-nvim"
       ];