Fix dark-colored description text in arc-green theme (#22908)

Fix #22873.

web_src/less/_base.less

@@ -651,6 +651,10 @@ a.commit-statuses-trigger {
   color: var(--color-text-dark);
 }
 
+.ui.search > .results .result .description {
+  color: var(--color-text-light-2);
+}
+
 .ui.search > .results .result .image {
   width: auto;
   height: auto;