Fix incorrect oldest sort in project list (#25806) (#25835)

Backport #25806 by @yp05327

sort type `oldest` should be `Asc`.
Added a test for this.

I see we have `SearchOrderBy` in db model, but we are using many
different ways to define the sort type.
~Maybe we can improve this later.~
↑ Improved in this PR

Co-authored-by: yp05327 <576951401@qq.com>

routers/web/org/projects.go

@@ -61,7 +61,7 @@ func Projects(ctx *context.Context) {
 		OwnerID:  ctx.ContextUser.ID,
 		Page:     page,
 		IsClosed: util.OptionalBoolOf(isShowClosed),
-		SortType: sortType,
+		OrderBy:  project_model.GetSearchOrderByBySortType(sortType),
 		Type:     projectType,
 	})
 	if err != nil {

routers/web/repo/projects.go

@@ -74,7 +74,7 @@ func Projects(ctx *context.Context) {
 		RepoID:   repo.ID,
 		Page:     page,
 		IsClosed: util.OptionalBoolOf(isShowClosed),
-		SortType: sortType,
+		OrderBy:  project_model.GetSearchOrderByBySortType(sortType),
 		Type:     project_model.TypeRepository,
 	})
 	if err != nil {