remove old completion config

lua/completion.lua

@@ -1,8 +0,0 @@
-local utils = require('utils')
-utils.opt('o', 'completeopt', 'menuone,noinsert,noselect')
-vim.cmd [[set shortmess+=c]]
-vim.g.completion_confirm_key = ""
-vim.g.completion_matching_strategy_list = {'exact', 'substring', 'fuzzy'}
--- <Tab> to navigate the completion menu
-utils.map('i', '<S-Tab>', 'pumvisible() ? "\\<C-p>" : "\\<Tab>"', {expr = true})
-utils.map('i', '<Tab>', 'pumvisible() ? "\\<C-n>" : "\\<Tab>"', {expr = true})