Webjob names are inconsistent when used to start/stop and list webjobs

## Describe the bug

Running `az webapp webjob continuous list` provides a list of webjobs with names that cannot be used to start/stop the webjob directly. It looks like the names provided is in the format of {appservicename}/{webjobname} whereas `start/stop` only accepts the webjob name

**Command Name**
`az webapp webjob continuous stop`
`az webapp webjob continuous start`

## To Reproduce:

- `az webapp webjob continuous list --name custom-appservice --resource-group CustomResourceGroupName`
- `az webapp webjob continuous stop --name custom-appservice --resource-group CustomResourceGroupName --webjob-name custom-appservice/worker`
- `az webapp webjob continuous start --name custom-appservice --resource-group CustomResourceGroupName --webjob-name custom-appservice/worker`

## Expected Behavior

Listing a list of webjobs using `az webapp webjob continuous list` will provide a list with names that can be used or `az webapp webjob continuous start/stop` accepts names provided by the list.

## Environment Summary
```
Windows-10-10.0.19041-SP0
Python 3.6.8
Installer: MSI

azure-cli 2.20.0 *

```
## Additional Context