remove util.OptionalBool and related functions (#29513)

and migrate affected code

_last refactoring bits to replace **util.OptionalBool** with
**optional.Option[bool]**_

(cherry picked from commit a3f05d0d98408bb47333b19f505b21afcefa9e7c)

Conflicts:
	services/repository/branch.go
	trivial context conflict

models/issues/label.go

@@ -12,6 +12,7 @@ import (
 
 	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/modules/label"
+	"code.gitea.io/gitea/modules/optional"
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/util"
 
@@ -126,7 +127,7 @@ func (l *Label) CalOpenOrgIssues(ctx context.Context, repoID, labelID int64) {
 	counts, _ := CountIssuesByRepo(ctx, &IssuesOptions{
 		RepoIDs:  []int64{repoID},
 		LabelIDs: []int64{labelID},
-		IsClosed: util.OptionalBoolFalse,
+		IsClosed: optional.Some(false),
 	})
 
 	for _, count := range counts {