**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
"""
    Checks if package should be excluded.
    :param package: package name (beginning of it)
    :param exclusion_list: list of excluded packages
    :return: true if package should be excluded
    """
    return any(package.startswith(excluded_package) for excluded_package in exclusion_list)
devel_all = [
    package
    for package in devel_all
    if not is_package_excluded(package=package, exclusion_list=PACKAGES_EXCLUDED_FOR_ALL)
]
devel_ci = devel_all
EXTRAS_REQUIREMENTS["doc"] = doc
EXTRAS_REQUIREMENTS["devel"] = devel  
EXTRAS_REQUIREMENTS["devel_hadoop"] = devel_hadoop  
EXTRAS_REQUIREMENTS["devel_all"] = devel_all
EXTRAS_REQUIREMENTS["devel_ci"] = devel_ci
def sort_extras_requirements() -> Dict[str, List[str]]: