Remove lsp_signature plugin

lua/custom/plugins/lsp_signature.lua

@@ -1,16 +0,0 @@
-return {
-  'ray-x/lsp_signature.nvim',
-  event = 'InsertEnter',
-  opts = {
-    bind = true,
-    doc_lines = 0,
-    close_timeout = 1000,
-    handler_opts = {
-      border = 'rounded',
-    },
-    toggle_key = '<C-k>',
-  },
-  config = function(_, opts)
-    require('lsp_signature').setup(opts)
-  end,
-}