Rename repo_model.SearchOrderByMap to repo_model.OrderByMap (#31359)

https://github.com/go-gitea/gitea/pull/30876#discussion_r1637112394

routers/web/explore/repo.go

@@ -63,7 +63,7 @@ func RenderRepoSearch(ctx *context.Context, opts *RepoSearchOptions) {
 		sortOrder = setting.UI.ExploreDefaultSort
 	}
 
-	if order, ok := repo_model.SearchOrderByFlatMap[sortOrder]; ok {
+	if order, ok := repo_model.OrderByFlatMap[sortOrder]; ok {
 		orderBy = order
 	} else {
 		sortOrder = "recentupdate"