Revert "fix(#1976): support non-standard $GIT_DIR (#2012)"

This reverts commit 517dee64c1.

lua/nvim-tree/utils.lua

@@ -5,11 +5,10 @@ local M = {
   debouncers = {},
 }
 
-local has_cygpath = vim.fn.executable "cygpath" == 1
-
 M.is_unix = vim.fn.has "unix" == 1
 M.is_macos = vim.fn.has "mac" == 1 or vim.fn.has "macunix" == 1
 M.is_wsl = vim.fn.has "wsl" == 1
+-- false for WSL
 M.is_windows = vim.fn.has "win32" == 1 or vim.fn.has "win32unix" == 1
 
 function M.str_find(haystack, needle)
@@ -39,26 +38,6 @@ function M.path_split(path)
   return path:gmatch("[^" .. path_separator .. "]+" .. path_separator .. "?")
 end
 
---- Normalise a path:
----  windows: replace slashes with backslashes
----   cygwin: resolve path first via cygpath
---- @param path string
---- @return string|nil nil on cygpath failure
-function M.norm_path(path)
-  if M.is_windows then
-    -- msys2 git support
-    if has_cygpath then
-      path = vim.fn.system("cygpath -w " .. vim.fn.shellescape(path))
-      if vim.v.shell_error ~= 0 then
-        return nil
-      end
-    end
-    path = path:gsub("/", "\\")
-  end
-
-  return path
-end
-
 ---Get the basename of the given path.
 ---@param path string
 ---@return string