Restore warning commit status (#27504)

Partial revert of https://github.com/go-gitea/gitea/pull/25839. This
commit status is used by a number of external integrations, so I think
we should not remove it (See
https://github.com/go-gitea/gitea/pull/25839#issuecomment-1729002077).
This is a rare case where an existing migration needed to be alterted to
avoid data loss.

---------

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Giteabot <teabot@gitea.io>

web_src/js/components/DashboardRepoList.vue

@@ -12,6 +12,7 @@ const commitStatus = {
   success: {name: 'octicon-check', color: 'green'},
   error: {name: 'gitea-exclamation', color: 'red'},
   failure: {name: 'octicon-x', color: 'red'},
+  warning: {name: 'gitea-exclamation', color: 'yellow'},
 };
 
 const sfc = {