### Apache Airflow version

2.5.2

### What happened

Not sure if this is a feature not a bug, but I can use KubernetesPodOperator fine without setting a kubernetes_conn_id.
For example:
```
start = KubernetesPodOperator(
        namespace="mynamespace",
        cluster_context="mycontext",
        security_context={ 'runAsUser': 1000 },
        name="hello",
        image="busybox",
        image_pull_secrets=[k8s.V1LocalObjectReference('prodregistry')],
        cmds=["sh", "-cx"],
        arguments=["echo Start"],
        task_id="Start",
        in_cluster=False,
        is_delete_operator_pod=True,
        config_file="/home/airflow/.kube/config",
    )
```

But if I add deferrable=True to this it won't work. It seems to require an explicit kubernetes_conn_id (which we don't configure).

Is not possible to the deferrable version to work as the non deferrable one?

### What you think should happen instead

I hoped that kpo deferrable would work the same as non deferrable.

### How to reproduce

Use KPO with deferrable=True but no kubernetes_conn_id setting

### Operating System

Debian 11

### Versions of Apache Airflow Providers

_No response_

### Deployment

Official Apache Airflow Helm Chart

### Deployment details

_No response_

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

- KPO
            - airflow connection
            - infer from k8s when in a cluster
            - 'default' namespace as a fallback
        Here we check when KPO omitted but we do have a conn where namespace defined.
        In this case, we should continue down the change.
        Here we mock not in k8s and therefore get 'default'.
        """
        k = KubernetesPodOperator(
            image="ubuntu:16.04",
            cmds=["bash", "-cx"],
            arguments=["echo 10"],
            task_id="task",
            name="hello",
            kubernetes_conn_id="my_conn",
        )
        mock_path.return_value.exists.return_value = False
        context = create_context(k)
        pod = k.build_pod_request_obj(context)
        mock_path.assert_called()
        assert pod.metadata.namespace == "default"
        mock_find.return_value = pod
        k.get_or_create_pod(
            pod_request_obj=pod,
            context=context,
        )
        mock_find.assert_called_once_with("default", context=context)
    @patch("pathlib.Path")
    @patch(f"{KPO_MODULE}.KubernetesPodOperator.find_pod")
    def test_omitted_namespace_no_conn(self, mock_find, mock_path):