Migrate `gl-order-n1` to Tailwind

What does this MR do and why?

Migrate gl-order-n1 to Tailwind

Migrates the gl-order-n1 CSS util to its Tailwind equivalent -gl-order-1.

MR acceptance checklist

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Before	After

CSS-in-Js diff

diff --git a/config/helpers/tailwind/css_in_js.js b/config/helpers/tailwind/css_in_js.js
index f4f758ebfdeb..a08b30c7e1b8 100644
--- a/config/helpers/tailwind/css_in_js.js
+++ b/config/helpers/tailwind/css_in_js.js
@@ -1,5 +1,5 @@
 /**
- * The following 574 definitions need to be migrated to Tailwind.
+ * The following 573 definitions need to be migrated to Tailwind.
  * Let's do this! 🚀
  */
 module.exports = {
@@ -351,7 +351,6 @@ module.exports = {
   '.align-self-center': { 'align-self': 'center' },
   '.md-align-self-center': { '@media (min-width: 768px)': { 'align-self': 'center' } },
   '.align-self-baseline': { 'align-self': 'baseline' },
-  '.order-n1': { order: '-1' },
   '.grid-tpl-rows-auto': { 'grid-template-rows': 'auto' },
   '.sm-grid-template-columns-2': {
     '@media (min-width: 576px)': { 'grid-template-columns': '1fr 1fr' },

Related to #456618