PubSub Publish task is successful even when no PubSub topic exists

### Expected Behavior

The PubSub Publish task should fail if the publish did not take place (when the topic itself did not exist).

### Actual Behaviour

The PubSub Publish task is successful when there is no PubSub topic.

### Steps To Reproduce

1. Ensure the PubSub topic does not exist.
2. Run the example flow of PubSub publish task.
3. Execution will be successful.

### Environment Information

- Kestra Version: 0.15.5
- Plugin version: 0.15.5
- Operating System (OS / Docker / Kubernetes): Docker
- Java Version (If not docker):

### Example flow

```yaml
id: pubsub-publish
namespace: dev
tasks:
- id: "publish"
type: "io.kestra.plugin.gcp.pubsub.Publish"
projectId:
serviceAccount: "{{ secret('GCP_SERVICE_ACCOUNT_JSON') }}"
topic: smantri-test
from:
- data: "{{ 'base64-encoded-string-1' | base64encode }}"
attributes:
testAttribute: KestraTest
messageId: '1234'
- data: "{{ 'base64-encoded-string-2' | base64encode }}"
- attributes:
testAttribute: KestraTest
```

Start at the io.kestra.plugin.gcp.pubsub.Publish task entry point and reproduce the example flow with the smantri-test topic absent. Trace how the publish operation reports success, then verify that execution fails when no topic exists and test the behavior against the reported PubSub environment.

Written by the indexing model from the issue text.