[php-src] Issue #20627: Cannot identify some avif images with getimagesize (returns false)

Issue: https://github.com/php/php-src/issues/20627
Author: cyberbeat

### Description

imagecreatefromavif works

This is output of "heif-info -d"

```
MIME type: image/avif
main brand: avif
compatible brands: mif1, miaf
Box: ftyp ----- (File Type)
size: 24   (header size: 8)
major brand: avif
minor version: 0
compatible brands: mif1,miaf

Box: meta ----- (Metadata)
size: 222   (header size: 12)
| Box: hdlr ----- (Handler Reference)
| size: 33   (header size: 12)
| pre_defined: 0
| handler_type: pict
| name: 
| 
| Box: pitm ----- (Primary Item)
| size: 14   (header size: 12)
| item_ID: 1
| 
| Box: iloc ----- (Item Location)
| size: 30   (header size: 12)
| item ID: 1
|   construction method: 0
|   data_reference_index: 0
|   base_offset: 0
|   extents: 254,59658 
| 
| Box: iinf ----- (Item Information)
| size: 35   (header size: 12)
| | Box: infe ----- (Item Info Entry)
| | size: 21   (header size: 12)
| | item_ID: 1
| | item_protection_index: 0
| | item_type: av01
| | item_name: 
| | hidden item: false
| 
| Box: iref ----- (Item Reference)
| size: 12   (header size: 12)
| 
| Box: iprp ----- (Item Properties)
| size: 86   (header size: 8)
| | Box: ipco ----- (Item Property Container)
| | size: 56   (header size: 8)
| | | index: 1
| | | Box: ispe ----- (Image Spatial Extents)
| | | size: 20   (header size: 12)
| | | image width: 1080
| | | image height: 1080
| | | 
| | | index: 2
| | | Box: av1C -----
| | | size: 12   (header size: 8)
| | | version: 1
| | | seq_profile: 1
| | | seq_level_idx_0: 31
| | | high_bitdepth: 1
| | | twelve_bit: 0
| | | monochrome: 0
| | | chroma_subsampling_x: 0
| | | chroma_subsampling_y: 0
| | | chroma_sample_position: 0
| | | initial_presentation_delay: not present
| | | config OBUs:
| | | 
| | | index: 3
| | | Box: pixi ----- (Pixel Information)
| | | size: 16   (header size: 12)
| | | bits_per_channel: 10,10,10
| | 
| | Box: ipma ----- (Item Property Association)
| | size: 22   (header size: 12)
| | associations for item ID: 1
| | | property index: 1 (essential: false)
| | | property index: 2 (essential: true)
| | | property index: 3 (essential: false)
```

and identify:

```
Format: AVIF (AV1 Image File Format)
  Mime type: image/avif
  Class: DirectClass
  Geometry: 1080x1080+0+0
  Units: Undefined
  Colorspace: sRGB
  Type: TrueColor
  Base type: Undefined
  Endianness: Undefined
  Depth: 10/16-bit
  Channels: 3.0
  Channel depth:
    Red: 16-bit
    Green: 16-bit
    Blue: 16-bit
```

### PHP Version

```plain
PHP 8.4.14 (cli) (built: Oct 23 2025 19:02:50) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.4.14, Copyright (c) Zend Technologies

Also tried 8.4.15
```

### Operating System

Ubuntu 24.04  / Opensuse Tumbleweed