docs: remove swatches for theme colors. (#29327)

Use the built-in utilities instead.

site/content/docs/4.3/getting-started/theming.md

@@ -276,7 +276,7 @@ We use a subset of all colors to create a smaller color palette for generating c
   {{< theme-colors.inline >}}
   {{- range (index $.Site.Data "theme-colors") }}
     <div class="col-md-4">
-      <div class="p-3 mb-3 swatch-{{ .name }}">{{ .name | title }}</div>
+      <div class="p-3 mb-3 bg-{{ .name }} {{ if or (eq .name "light") (eq .name "warning") }}text-dark{{ else }}text-white{{ end }}">{{ .name | title }}</div>
     </div>
   {{ end -}}
   {{< /theme-colors.inline >}}

site/static/docs/4.3/assets/scss/_colors.scss

@@ -9,13 +9,6 @@
   }
 }
 
-@each $color, $value in $theme-colors {
-  .swatch-#{$color} {
-    color: color-yiq($value);
-    background-color: #{$value};
-  }
-}
-
 @each $color, $value in $grays {
   .swatch-#{$color} {
     color: color-yiq($value);