Some performance optimization on dashboard and issues page (#29010)

This PR do some loading speed optimization for feeds user interface
pages.
- Load action users batchly but not one by one.
- Load action repositories batchly but not one by one.
- Load action's Repo Owners batchly but not one by one.
- Load action's possible issues batchly but not one by one.
- Load action's possible comments batchly but not one by one.

(cherry picked from commit aed3b53abdd02a3ffbf9e8eb90272ff567333073)

models/repo/repo_list.go

@@ -63,6 +63,41 @@ func RepositoryListOfMap(repoMap map[int64]*Repository) RepositoryList {
 	return RepositoryList(ValuesRepository(repoMap))
 }
 
+func (repos RepositoryList) LoadUnits(ctx context.Context) error {
+	if len(repos) == 0 {
+		return nil
+	}
+
+	// Load units.
+	units := make([]*RepoUnit, 0, len(repos)*6)
+	if err := db.GetEngine(ctx).
+		In("repo_id", repos.IDs()).
+		Find(&units); err != nil {
+		return fmt.Errorf("find units: %w", err)
+	}
+
+	unitsMap := make(map[int64][]*RepoUnit, len(repos))
+	for _, unit := range units {
+		if !unit.Type.UnitGlobalDisabled() {
+			unitsMap[unit.RepoID] = append(unitsMap[unit.RepoID], unit)
+		}
+	}
+
+	for _, repo := range repos {
+		repo.Units = unitsMap[repo.ID]
+	}
+
+	return nil
+}
+
+func (repos RepositoryList) IDs() []int64 {
+	repoIDs := make([]int64, len(repos))
+	for i := range repos {
+		repoIDs[i] = repos[i].ID
+	}
+	return repoIDs
+}
+
 // LoadAttributes loads the attributes for the given RepositoryList
 func (repos RepositoryList) LoadAttributes(ctx context.Context) error {
 	if len(repos) == 0 {