az interactive trhows an error after upgrade to az 2.7.0

### **This is autogenerated. Please review and update as needed.**

## Describe the bug

**Command Name**
`az interactive`

**Errors:**
```
cannot import name 'ENV_ADDITIONAL_USER_AGENT'
Traceback (most recent call last):
Temp\pip-install-_kvuguic\knack\knack\cli.py, ln 215, in invoke
azure\cli\core\commands\__init__.py, ln 654, in execute
azure\cli\core\commands\__init__.py, ln 718, in _run_jobs_serially
azure\cli\core\commands\__init__.py, ln 711, in _run_job
Local\Temp\pip-install-_kvuguic\six\six.py, ln 703, in reraise
azure\cli\core\commands\__init__.py, ln 688, in _run_job
azure\cli\core\commands\__init__.py, ln 325, in __call__
site-packages\azure\cli\core\__init__.py, ln 545, in default_command_handler
azure\cli\command_modules\interactive\custom.py, ln 41, in start_shell
.azure\cliextensions\interactive\azext_interactive\__init__.py, ln 10, in start_shell
from .azclishell.app import AzInteractiveShell
cliextensions\interactive\azext_interactive\azclishell\app.py, ln 31, in
from azure.cli.core.commands.client_factory import ENV_ADDITIONAL_USER_AGENT
ImportError: cannot import name 'ENV_ADDITIONAL_USER_AGENT'
```

## To Reproduce:
Steps to reproduce the behavior. Note that argument values have been redacted, as they may contain sensitive information.

- Upgrade az to 2.7.0
- `az interactive`

## Expected Behavior
az interactive prompt is opened

## Environment Summary
```
Windows-10-10.0.18362-SP0
Python 3.6.6
Installer: MSI

azure-cli 2.7.0

Extensions:
interactive 0.4.3

```
## Additional Context