Move gray color variables above theme related colors

- This will replicate changes in !24268 and minimze conflicts.
- Hi @nfriend!

app/assets/stylesheets/framework/variables.scss

@@ -98,6 +98,18 @@ $red-800: #8b2615;
 $red-900: #711e11;
 $red-950: #4b140b;
 
+$gray-50: #fafafa;
+$gray-100: #f2f2f2;
+$gray-200: #dfdfdf;
+$gray-300: #cccccc;
+$gray-400: #bababa;
+$gray-500: #a7a7a7;
+$gray-600: #919191;
+$gray-700: #707070;
+$gray-800: #4f4f4f;
+$gray-900: #2e2e2e;
+$gray-950: #1f1f1f;
+
 // GitLab themes
 
 $indigo-50: #f7f7ff;
@@ -112,18 +124,6 @@ $indigo-800: #393982;
 $indigo-900: #292961;
 $indigo-950: #1a1a40;
 
-$gray-50: #fafafa;
-$gray-100: #f2f2f2;
-$gray-200: #dfdfdf;
-$gray-300: #cccccc;
-$gray-400: #bababa;
-$gray-500: #a7a7a7;
-$gray-600: #919191;
-$gray-700: #707070;
-$gray-800: #4f4f4f;
-$gray-900: #2e2e2e;
-$gray-950: #1f1f1f;
-
 $theme-blue-50: #f4f8fc;
 $theme-blue-100: #e6edf5;
 $theme-blue-200: #c8d7e6;