Remove fa-external-link from CSS

And add changelog

app/assets/stylesheets/fontawesome_custom.scss

@@ -101,10 +101,6 @@
   content: '\f071';
 }
 
-.fa-external-link::before {
-  content: '\f08e';
-}
-
 .fa-spinner::before {
   content: '\f110';
 }

changelogs/unreleased/225953-replace-fa-external-link-icons-with-gitlab-svg-external-link-icon.yml

+---
+title: Replace external-link icons with GitLab SVG
+merge_request: 45685
+author:
+type: changed