**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
"""Adds extras for all additional extras."""
    for extra_name, extra_requirement in ADDITIONAL_EXTRAS_REQUIREMENTS.items():
        EXTRAS_REQUIREMENTS[extra_name] = extra_requirement
add_extras_for_all_providers()
add_additional_extras()
EXTRAS_DEPRECATED_ALIASES: Dict[str, str] = {
    'atlas': 'apache.atlas',
    'aws': 'amazon',
    'azure': 'microsoft.azure',
    'cassandra': 'apache.cassandra',
    'crypto': '',  
    'druid': 'apache.druid',
    'gcp': 'google',
    'gcp_api': 'google',
    'hdfs': 'apache.hdfs',
    'hive': 'apache.hive',
    'kubernetes': 'cncf.kubernetes',
    'mssql': 'microsoft.mssql',
    'pinot': 'apache.pinot',
    'qds': 'qubole',
    's3': 'amazon',
    'spark': 'apache.spark',
    'webhdfs': 'apache.webhdfs',
    'winrm': 'microsoft.winrm',
}
EXTRAS_DEPRECATED_ALIASES_NOT_PROVIDERS: List[str] = [
    "crypto",
    "webhdfs",
]
def add_extras_for_all_deprecated_aliases() -> None: