`az network private-link-resource list` - has no result for Cognitive Services Accounts

**Describe the bug**

Querying for for the group ID of a Cognitive Services Account returns an empty result

**To Reproduce**

When you run:
```
az network private-link-resource list -g jfk-rg-modev -n jfk-cognitive-services-modev --type Microsoft.CognitiveServices/accounts
```

You get:
```
Resource ID will be ignored since other three arguments have been provided.
[]
```

**Expected behavior**

Looking through unit tests for private endpoints leads you to assume that the expected result for this query should be `account`.

Unit test: https://github.com/Azure/azure-cli/blob/4e68492d4d03a2338d27771a58ee45e9e38ea3ab/src/azure-cli/azure/cli/command_modules/cognitiveservices/tests/latest/test_private_endpoint.py#L54

**Environment summary**
```
azure-cli 2.11.1
core 2.11.1
telemetry 1.0.5 *
Python location '/opt/az/bin/python3'
Extensions directory '/home/glenn/.azure/cliextensions'
Python (Linux) 3.6.10 (default, Aug 28 2020, 06:39:53)
[GCC 9.3.0]
```
azure-cli version 2.11.1

**Additional context**
n/a