**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
with mock.patch.object(PodLauncher, 'log') as mock_logger:
            volume_mount = k8s.V1VolumeMount(
                name='test-volume',
                mount_path='/tmp/test_volume',
                sub_path=None,
                read_only=False
            )
            volume = k8s.V1Volume(
                name='test-volume',
                persistent_volume_claim=k8s.V1PersistentVolumeClaimVolumeSource(
                    claim_name='test-volume'
                )
            )
            args = ["echo \"retrieved from mount\" > /tmp/test_volume/test.txt "
                    "&& cat /tmp/test_volume/test.txt"]
            k = KubernetesPodOperator(