**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
"""
    Add extras for all deprecated aliases. Requirements for those deprecated aliases are the same
    as the extras they are replaced with.
    The requirements are not copies - those are the same lists as for the new extras. This is intended.
    Thanks to that if the original extras are later extended with providers, aliases are extended as well.
    """
    for alias, extra in EXTRAS_DEPRECATED_ALIASES.items():
        requirements = EXTRAS_REQUIREMENTS.get(extra) if extra != '' else []
        if requirements is None:
            raise Exception(f"The extra {extra} is missing for deprecated alias {alias}")
        EXTRAS_REQUIREMENTS[alias] = requirements
def add_all_deprecated_provider_packages() -> None:
    """
    For deprecated aliases that are providers, we will swap the providers requirements to instead
    be the provider itself.
    e.g. {"kubernetes": ["kubernetes>=3.0.0, <12.0.0", ...]} becomes
    {"kubernetes": ["apache-airflow-provider-cncf-kubernetes"]}
    """
    for alias, provider in EXTRAS_DEPRECATED_ALIASES.items():
        if alias in EXTRAS_DEPRECATED_ALIASES_NOT_PROVIDERS:
            continue
        replace_extra_requirement_with_provider_packages(alias, [provider])
add_extras_for_all_deprecated_aliases()
ALL_PROVIDERS = list(PROVIDERS_REQUIREMENTS.keys())
ALL_DB_PROVIDERS = [