Fix schedule tasks bugs (#28691)

Fix #28157 

This PR fix the possible bugs about actions schedule.

## The Changes

- Move `UpdateRepositoryUnit` and `SetRepoDefaultBranch` from models to
service layer
- Remove schedules plan from database and cancel waiting & running
schedules tasks in this repository when actions unit has been disabled
or global disabled.
- Remove schedules plan from database and cancel waiting & running
schedules tasks in this repository when default branch changed.

models/repo/repo_unit.go

@@ -283,29 +283,3 @@ func UpdateRepoUnit(ctx context.Context, unit *RepoUnit) error {
 	_, err := db.GetEngine(ctx).ID(unit.ID).Update(unit)
 	return err
 }
-
-// UpdateRepositoryUnits updates a repository's units
-func UpdateRepositoryUnits(ctx context.Context, repo *Repository, units []RepoUnit, deleteUnitTypes []unit.Type) (err error) {
-	ctx, committer, err := db.TxContext(ctx)
-	if err != nil {
-		return err
-	}
-	defer committer.Close()
-
-	// Delete existing settings of units before adding again
-	for _, u := range units {
-		deleteUnitTypes = append(deleteUnitTypes, u.Type)
-	}
-
-	if _, err = db.GetEngine(ctx).Where("repo_id = ?", repo.ID).In("type", deleteUnitTypes).Delete(new(RepoUnit)); err != nil {
-		return err
-	}
-
-	if len(units) > 0 {
-		if err = db.Insert(ctx, units); err != nil {
-			return err
-		}
-	}
-
-	return committer.Commit()
-}