**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
}
CORE_EXTRAS_REQUIREMENTS: Dict[str, List[str]] = {
    'async': async_packages,
    'celery': celery,  
    'cgroups': cgroups,
    'cncf.kubernetes': kubernetes,  
    'dask': dask,
    'deprecated_api': deprecated_api,
    'github_enterprise': flask_appbuilder_authlib,
    'google_auth': flask_appbuilder_authlib,
    'kerberos': kerberos,
    'ldap': ldap,
    'leveldb': leveldb,
    'pandas': pandas,
    'password': password,
    'rabbitmq': rabbitmq,
    'sentry': sentry,
    'statsd': statsd,
    'virtualenv': virtualenv,
}
EXTRAS_REQUIREMENTS: Dict[str, List[str]] = deepcopy(CORE_EXTRAS_REQUIREMENTS)
def add_extras_for_all_providers() -> None:
    """
    Adds extras for all providers.
    By default all providers have the same extra name as provider id, for example
    'apache.hive' extra has 'apache.hive' provider requirement.
    """
    for provider_name, provider_requirement in PROVIDERS_REQUIREMENTS.items():
        EXTRAS_REQUIREMENTS[provider_name] = provider_requirement
def add_additional_extras() -> None: