Sort users and orgs on explore by recency by default (#24279)

This gives more "freshness" to the explore page. So it's not just the
same X users on the explore page by default, now it matches the same
sort as the repos on the explore page.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

routers/web/explore/org.go

@@ -30,6 +30,10 @@ func Organizations(ctx *context.Context) {
 		visibleTypes = append(visibleTypes, structs.VisibleTypeLimited, structs.VisibleTypePrivate)
 	}
 
+	if ctx.FormString("sort") == "" {
+		ctx.SetFormString("sort", UserSearchDefaultSortType)
+	}
+
 	RenderUserSearch(ctx, &user_model.SearchUserOptions{
 		Actor:       ctx.Doer,
 		Type:        user_model.UserTypeOrganization,