az lab vm list fails with an MSI error when running from CloudShell

## Describe the bug

**Command Name**
`az lab vm list`

**Errors:**
```
AzureResponseError: Failed to connect to MSI. Please make sure MSI is configured correctly.
Get Token request returned:
```

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

- `az lab vm list --lab-name {} --resource-group {}`

## Expected Behavior
I can see the list of VMs

## Environment Summary
```
Linux-4.15.0-1106-azure-x86_64-with-debian-10.2 (Cloud Shell)
Python 3.6.10
Installer: DEB

azure-cli 2.18.0
azure-cli-ml 1.20.0

Extensions:
azure-iot 0.10.8
ai-examples 0.2.5
azure-cli-ml 1.20.0

```
## Additional Context