`object|<Class>` docblocks in `DispatchTrait` break metadata warmup under symfony/type-info 7.4 (`Cannot create union with both "object" and class type`)

## API Platform version

4.3.13

## PHP version

8.4

## Description

`api-platform/core` 4.3 ships redundant union docblocks of the form
`object|` in its own source:

- `src/Symfony/Messenger/DispatchTrait.php:28` → `@param object|Envelope $message`
- `src/Doctrine/Common/Messenger/DispatchTrait.php:28` → `@param object|Envelope $message`

With `symfony/type-info` 7.4 installed, the `PhpStanExtractor` that API Platform
wires as `api_platform.property_info.php_stan_extractor` throws an Exception while building
the type graph whenever it parses such a docblock:

```
Symfony\Component\TypeInfo\Exception\InvalidArgumentException:
Cannot create union with both "object" and class type.
at vendor/symfony/type-info/Type/UnionType.php:75
```

`object|Envelope` is redundant — `object` already subsumes every class type.
The legacy `symfony/property-info` `Type` model tolerated this; `symfony/type-info`
7.4 rejects it hard.

This regressed `cache:clear` / routing warmup on the Symfony 7.3 → 7.4 bump.

## Relation to #8201 / #8206

PR #8206 (released in 4.3.10) isolated the **framework** `property_info` service
from API Platform's extractors via private `api_platform.property_info.*` tags +
a bridge compiler pass. That fixed the path where API Platform's `PhpStanExtractor`
leaked into the framework service (Sylius `@template T of object` crash).

It does **not** cover this case: API Platform's *own* `PhpStanExtractor` still
parses `object|` docblocks during metadata warmup and hits the same
`type-info` exception. The remaining 4.3 path is still affected.

## How to reproduce

Minimal standalone reproduction (public packages only, no app kernel needed):
**https://gist.github.com/schmunk42/3357f3d0fdffe11e977812900355cefd**

```bash
composer install
php repro.php
```

```
PHP : 8.4.22
api-platform/core: v4.3.13
symfony/type-info: v7.4.9
symfony/property-info: v7.4.8
------------------------------------------------------------
[KO] Symfony\Component\TypeInfo\Exception\InvalidArgumentException: Cannot create union with both "object" and class type.
thrown from: .../symfony/type-info/Type/UnionType.php:75
```

The gist invokes the exact extractor API Platform wires as
`api_platform.property_info.php_stan_extractor` directly
**Title:**

---
on a property whose
docblock mirrors the `DispatchTrait` shape (`@var object|Envelope`).

You can also confirm the offending docblocks directly:

```bash
grep -rn "object|Envelope" vendor/api-platform/core/src
# src/Doctrine/Common/Messenger/DispatchTrait.php:28
# src/Symfony/Messenger/DispatchTrait.php:28
```

## Possible solution

Drop the redundant `|Envelope` from both `DispatchTrait` docblocks — the
method already declares `object $message` / `: Envelope` in the signature, so
the docblock carries no extra information:

```diff
- /**
- * @param object|Envelope $message
- */
private function dispatch(object $message): Envelope
```

(or `@param object $message` if a docblock is desired). This keeps the source
free of redundant unions that `symfony/type-info` 7.4 rejects.