Remove module that set custom symbols for lspkind

Since now lspkind plugin contains a preset setting those same symbols,
there is no longer the need of having them set and versioned in this
repo.

nvim/language_server.vim

@@ -50,6 +50,5 @@ let g:completion_trigger_on_delete = 1  " not v:true, 1. ¯\_(ツ)_/¯
 
 " lspkind-nvim
 lua << EOF
-local symbol_map = require('lsp_symbols')
-require('lspkind').init({with_text=false, symbol_map=symbol_map})
+require('lspkind').init({with_text=false, preset='codicons'})
 EOF

nvim/lua/lsp_symbols.lua

@@ -1,34 +0,0 @@
--- Use Codeicon symbols shown here:
--- https://code.visualstudio.com/docs/editor/intellisense#_types-of-completions
--- https://microsoft.github.io/vscode-codicons/dist/codicon.html
--- Unicode symbols taken from VS Code source code (search symbol- entries):
--- https://github.com/microsoft/vscode/blob/main/src/vs/base/common/codicons.ts#L113-L556
-local lspkind_symbol_map = {
-    Text = '',
-    Method = '',
-    Function = '',
-    Constructor = '',
-    Field = '',
-    Variable = '',
-    Class = '',
-    Interface = '',
-    Module = '',
-    Property = '',
-    Unit = '',
-    Value = '',
-    Enum = '',
-    Keyword = '',
-    Snippet = '',
-    Color = '',
-    File = '',
-    Reference = '',
-    Folder = '',
-    EnumMember = '',
-    Constant = '',
-    Struct = '',
-    Event = '',
-    Operator = '',
-    TypeParameter = '',
-}
-
-return lspkind_symbol_map