global options are not taked into account when route options are defined partially

### Prerequisites

- [X] I have written a descriptive issue title
- [X] I have searched existing issues to ensure the bug has not already been reported

### Fastify version

5.2.0

### Plugin version

8.0.1

### Node.js version

22.12.0

### Operating system

macOS

### Operating system version (i.e. 20.04, 11.3, 10)

15.1.1

### Description

Given this plugin registered has follow :

```ts
function onInvalidRequestPayload(
...parameters: Parameters>
) {
return {
statusCode: HTTPStatusCodeEnum.BadRequest,
code: 'Invalid Request Payload',
name: 'InvalidRequestPayload',
error: 'Invalid Request Payload',
message: `Payload is not ${parameters[0]} encoded. ${parameters[2].message}`,
};
}

function onUnsupportedRequestEncoding(
...parameters: Parameters>
) {
return {
statusCode: HTTPStatusCodeEnum.UnsupportedMediaType,
code: 'Unsupported Media Type',
name: 'UnsupportedMediaType',
error: 'Unsupported Media Type',
message: `${parameters[0]} encoding is not supported`,
};
}

await fastify.register(compressPlugin, {
global: true,
onInvalidRequestPayload: onInvalidRequestPayload,
removeContentLengthHeader: false,
onUnsupportedRequestEncoding: onUnsupportedRequestEncoding,
});
```

if a route is registered has follow :

```ts
fastifyInstance.withTypeProvider().route({
method: 'POST',
url: '/',
schema: {
body: BODY,
response: {
[HTTPStatusCodeEnum.OK]: RESPONSE,
},
},
decompress: {
// eslint-disable-next-line @typescript-eslint/explicit-function-return-type, @typescript-eslint/promise-function-async
onUnsupportedRequestEncoding: function (encoding, request, reply) {
// we duplicate this here because our preParsing hook is not triggered in this context
request.monitoringScanEvent =
MonitoringScanEvent.CreateWithoutTraceId().setName('a');

return onUnsupportedRequestEncoding(encoding, request, reply);
},
},
bodyLimit: 14_680_064, // 14M
preParsing: (request, _reply, _payload, done): void => {
request.monitoringScanEvent =
MonitoringScanEvent.CreateWithoutTraceId().setName('a');

done();
},
errorHandler: async (error, request, reply): Promise => {
request.monitoringScanEvent.setStatus('error');
request.monitoringScanEvent.mergeWithMessage({
error: error.message,
});

fastifyInstance.errorHandler(error, request, reply);
},
onResponse: async (request): Promise => {
await fastifyInstance.httpClient
.getInstance()
.v1.monitoring.postScanEvent(
request.monitoringScanEvent.toObject(),
request.monitoringScanEvent.getTraceId(),
);
},
handler: async (request, reply): Promise => {
const response = await handler(
fastifyInstance,
request.body,
request.headers,
request.monitoringScanEvent,
request.log,
);

return await reply.status(HTTPStatusCodeEnum.OK).send(response);
},
});
```

This `onInvalidRequestPayload` hook provided in the global configuration at plugin registration is not taken into account, instead, the 'default' hook from the plugin is used.

### Link to code that reproduces the bug

_No response_

### Expected Behavior

This plugin should merge every options with :

- route option first
- global option at registration in second
- fallback to default plugin option last