Migrate `gl-fill-current-color` to Tailwind

What does this MR do and why?

Migrate gl-fill-current-color to Tailwind

Migrates gl-fill-current-color to its Tailwind equivalent gl-fill-current.

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..cfb565d63728 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 = {
@@ -592,7 +592,6 @@ module.exports = {
   '.md-px-7': { '@media (min-width: 768px)': { 'padding-left': '2rem', 'padding-right': '2rem' } },
   '.lg-pt-3': { '@media (min-width: 992px)': { 'padding-top': '0.5rem' } },
   '.lg-pr-5': { '@media (min-width: 992px)': { 'padding-right': '1rem' } },
-  '.fill-current-color': { fill: 'currentColor' },
   '.text-left\\!': { 'text-align': 'left !important' },
   '.text-center\\!': { 'text-align': 'center !important' },
   '.reset-text-align': { 'text-align': 'inherit' },

Related to #456618 (closed)