Private Group Id in Capitals not accepted for few resources

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**Describe the bug**

For few of the services, the Azure CLI errors out stating that the Group Id is not supported, For example, for some resources, it works when a Group id is sent out in ALL CAPS but for some it fails.

**To Reproduce**

1. Create a RA-GRS Storage Account along with necessary vnet and subnets for Private Endpoint.
2. Try to create a private endpoint for the secondary table endpoint for the storage account like this -
3. If you try to create a private endpoint for some other resource like Azure Data Factory and pass the Group ID in All CAPS, it works as expected as well.
```
az network private-endpoint create --resource-group RGP-NET --vnet-name NET-VNET-D --subnet SNET-D-PRVLNK --connection-name AR-AZ-D-USE1-NET-PVE-ST-SPEND-TABLE_SECONDARY --group-id TABLE_SECONDARY --private-connection-resource-id "/subscriptions/aaaaaaaa-aaaa-aaaa-a5f3-7fae0325ce24/resourceGroups/RGP-APP/providers/Microsoft.Storage/storageAccounts/teststorageaccount" --name NET-PVE-ST-TABLE_SECONDARY
BadRequestError: (InvalidValuesForRequestParameters) Call to Microsoft.Storage/storageAccounts failed. Error message: Values for request parameters are invalid: GroupId: TABLE_SECONDARY.
```
Now, if you try the following command with the group id in small case, it goes ahead and works as expected -
```
az network private-endpoint create --resource-group RGP-NET --vnet-name NET-VNET-D --subnet SNET-D-PRVLNK --connection-name AR-AZ-D-USE1-NET-PVE-ST-SPEND-TABLE_SECONDARY --group-id table_secondary--private-connection-resource-id "/subscriptions/aaaaaaaa-aaaa-aaaa-a5f3-7fae0325ce24/resourceGroups/RGP-APP/providers/Microsoft.Storage/storageAccounts/teststorageaccount" --name NET-PVE-ST-TABLE_SECONDARY
```
**Expected behavior**
The private endpoint is created as long as the correct group id is passed, no matter if it is in ALL CAPS or ALL SMALL.

**Environment summary**

Azure Shell
```
pranav@Azure:~$ az --version
azure-cli 2.18.0

core 2.18.0
telemetry 1.0.6

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

Python location '/opt/az/bin/python3'
Extensions directory '/home/pranav/.azure/cliextensions'
Extensions system directory '/opt/az/lib/python3.6/site-packages/azure-cli-extensions'

Python (Linux) 3.6.10 (default, Jan 15 2021, 09:54:35)
[GCC 8.3.0]

Legal docs and information: aka.ms/AzureCliLegal

Your CLI is up-to-date.
```