**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
env_vars = [
            k8s.V1EnvVar(
                name="ENV1",
                value="val1"
            ),
            k8s.V1EnvVar(
                name="ENV2",
                value="val2"
            ),
            k8s.V1EnvVar(
                name="ENV3",
                value_from=k8s.V1EnvVarSource(
                    field_ref=k8s.V1ObjectFieldSelector(
                        field_path="status.podIP"
                    )
                )
            ),
        ]