**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
"""List extras."""
        print("\n".join(wrap(", ".join(EXTRAS_REQUIREMENTS.keys()), 100)))
def git_version(version_: str) -> str:
    """
    Return a version to identify the state of the underlying git repo. The version will
    indicate whether the head of the current git-backed working directory is tied to a
    release tag or not : it will indicate the former with a 'release:{version}' prefix
    and the latter with a '.dev0' suffix. Following the prefix will be a sha of the current
    branch head. Finally, a "dirty" suffix is appended to indicate that uncommitted
    changes are present.
    :param str version_: Semver version
    :return: Found Airflow version in Git repo
    :rtype: str
    """
    try:
        import git
        try:
            repo = git.Repo(os.path.join(*[my_dir, '.git']))
        except git.NoSuchPathError:
            logger.warning('.git directory not found: Cannot compute the git version')
            return ''
        except git.InvalidGitRepositoryError:
            logger.warning('Invalid .git directory not found: Cannot compute the git version')
            return ''
    except ImportError:
        logger.warning('gitpython not found: Cannot compute the git version.')
        return ''
    if repo:
        sha = repo.head.commit.hexsha
        if repo.is_dirty():