Some page numbers are excluded from document index

### Bug
Some page numbers are excluded from document index.

Example: [ECE37e_-02.pdf](https://github.com/user-attachments/files/18709090/ECE37e_-02.pdf)


Markdown output:
```markdown
## UN Regulation on uniform provisions concerning the approval of vehicles with regard to Driver Control Assistance Systems

## Contents

3

5

5

8

9

70

| | | Page |
|---------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|
| | Introduction ............................................................................................................... | |
| 1. | Scope ......................................................................................................................... | |
| 2. | Definitions ................................................................................................................. | |
| 3. | Application for approval ............................................................................................ | 8 |
| 4. | Approval .................................................................................................................... | |
| 5. | General Specifications ............................................................................................... | |
| 6. | Additional Specifications for DCAS Features ........................................................... | 21 |
```

### Steps to reproduce
```shell
docling --debug-visualize-layout ECE37e_-02.pdf
```

### Docling version
```
Docling version: 2.19.0
Docling Core version: 2.17.2
Docling IBM Models version: 3.3.0
Docling Parse version: 3.3.0
Python: cpython-312 (3.12.8)
Platform: macOS-15.3-arm64-arm-64bit
```

### Python version
```
Python 3.12.8
```