**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 self.assertLogs(k.log, level=logging.DEBUG) as cm:
            k.execute(context)
            expected_line = textwrap.dedent("""\
            DEBUG:airflow.task.operators:Starting pod:
            api_version: v1
            kind: Pod
            metadata:
              annotations: {}
              cluster_name: null
              creation_timestamp: null
              deletion_grace_period_seconds: null\
            """).strip()
            self.assertTrue(any(line.startswith(expected_line) for line in cm.output))
        actual_pod = self.api_client.sanitize_for_serialization(k.pod)
        expected_dict = {'apiVersion': 'v1',
                         'kind': 'Pod',
                         'metadata': {'annotations': {},
                                      'labels': {},
                                      'name': 'memory-demo',
                                      'namespace': 'mem-example'},
                         'spec': {'affinity': {},
                                  'containers': [{'args': ['--vm',
                                                           '1',
                                                           '--vm-bytes',
                                                           '150M',
                                                           '--vm-hang',
                                                           '1'],
                                                  'command': ['stress'],
                                                  'env': [],
                                                  'envFrom': [],