**Apache Airflow version**:  1.10.10


**Kubernetes version (if you are using kubernetes)** (use `kubectl version`): v1.15.11

KubernetesPodOperator truncates logs when container produces more than 10 lines of logs before execution of `read_pod_logs` function. Is there any reason to make 10 as default value for `tail_lines` argument ?
```python
    def read_pod_logs(self, pod: V1Pod, tail_lines: int = 10):
        """Reads log from the POD"""
        try:
            return self._client.read_namespaced_pod_log(
                name=pod.metadata.name,
                namespace=pod.metadata.namespace,
                container='base',
                follow=True,
                tail_lines=tail_lines,
                _preload_content=False
            )
        except BaseHTTPError as e:
            raise AirflowException(
                'There was an error reading the kubernetes API: {}'.format(e)
            )
```
kubernetes_tests/test_kubernetes_pod_operator.py
from airflow.utils.state import State
        configmap_name = "test-config-map"
        env_from = [k8s.V1EnvFromSource(config_map_ref=k8s.V1ConfigMapEnvSource(
            name=configmap_name
        ))]
        
        k = KubernetesPodOperator(
            namespace='default',
            image="ubuntu:16.04",
            cmds=["bash", "-cx"],
            arguments=["echo 10"],
            labels={"foo": "bar"},
            name="test-" + str(random.randint(0, 1000000)),
            task_id="task" + self.get_current_task_name(),
            in_cluster=False,
            do_xcom_push=False,
            env_from=env_from
        )
        
        mock_monitor.return_value = (State.SUCCESS, None)
        context = create_context(k)
        k.execute(context)
        self.assertEqual(
            mock_start.call_args[0][0].spec.containers[0].env_from, env_from
        )
    @mock.patch("airflow.kubernetes.pod_launcher.PodLauncher.start_pod")
    @mock.patch("airflow.kubernetes.pod_launcher.PodLauncher.monitor_pod")
    @mock.patch("airflow.kubernetes.kube_client.get_kube_client")
    def test_envs_from_secrets(self, mock_client, monitor_mock, start_mock):