Error running az contianer exec

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

## Describe the bug

**Command Name**
`az container exec`

**Errors:**
```
The command failed with an unexpected error. Here is the traceback:
'ContainerInstanceManagementClient' object has no attribute 'container'
Traceback (most recent call last):
File "/opt/az/lib/python3.6/site-packages/knack/cli.py", line 231, in invoke
cmd_result = self.invocation.execute(args)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 657, in execute
raise ex
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 720, in _run_jobs_serially
results.append(self._run_job(expanded_arg, cmd_copy))
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 691, in _run_job
result = cmd_copy(params)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 328, in __call__
return self.handler(*args, **kwargs)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/command_operation.py", line 121, in handler
return op(**command_args)
File "/opt/az/lib/python3.6/site-packages/azure/cli/command_modules/container/custom.py", line 609, in container_exec
container_client = cf_container(cmd.cli_ctx)
File "/opt/az/lib/python3.6/site-packages/azure/cli/command_modules/container/_client_factory.py", line 18, in cf_container
return _container_instance_client_factory(cli_ctx).container
AttributeError: 'ContainerInstanceManagementClient' object has no attribute 'container'

```

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

- `az container exec --exec-command='/bin/bash' --subscription={} -g {} -n {}`

## Expected Behavior

## Environment Summary
```
Linux-5.11.0-34-generic-x86_64-with-debian-bullseye-sid, Ubuntu 20.04.3 LTS
Python 3.6.10
Installer: DEB

azure-cli 2.28.0 *

```
## Additional Context