**Apache Airflow version**: 2.0.1

**Environment**:

- **Cloud provider or hardware configuration**: AWS

**What happened**:
I have Airflow with Cloudwatch-based remote logging running. I also have `BashOperator` that does, for example, `rsync` with invalid parameters, for example `rsync -av test test`. The output of the `rsync` error is formatted and contains empty line. Once that empty line is logged to the Cloudwatch, i receive an error:
```
2021-04-06 19:29:22,318] /home/airflow/.local/lib/python3.6/site-packages/watchtower/__init__.py:154 WatchtowerWarning: Failed to deliver logs: Parameter validation failed:
Invalid length for parameter logEvents[5].message, value: 0, valid range: 1-inf
[2021-04-06 19:29:22,320] /home/airflow/.local/lib/python3.6/site-packages/watchtower/__init__.py:158 WatchtowerWarning: Failed to deliver logs: None
```

So basically empty lines can't be submitted to the Cloudwatch and as result the whole output of the process doesn't appear in logs.

**What you expected to happen**:

I expect to have an output of the bash command in logs. Empty lines can be skipped or replaced with something.

**How to reproduce it**:

For example: run `BashOperator` with `rsync` command that fails on Airflow with Cloudwatch-based remote logging. It could be any other command that produces empty line in the output.
setup.py
'openfaas': [],
    'opsgenie': http_provider,
    'oracle': oracle,
    'pagerduty': pagerduty,
    'papermill': papermill,
    'plexus': plexus,
    'postgres': postgres,
    'presto': presto,
    'qubole': qubole,
    'redis': redis,
    'salesforce': salesforce,
    'samba': samba,
    'segment': segment,
    'sendgrid': sendgrid,
    'sftp': ssh,
    'singularity': singularity,
    'slack': slack,
    'snowflake': snowflake,
    'sqlite': [],
    'ssh': ssh,
    'tableau': tableau,
    'telegram': telegram,
    'trino': trino,
    'vertica': vertica,
    'yandex': yandex,
    'zendesk': zendesk,
}
ADDITIONAL_EXTRAS_REQUIREMENTS: Dict[str, List[str]] = {
    'apache.atlas': atlas,
    'apache.webhdfs': webhdfs,