[BUG][Resource Graph] Resource Graph API returns inconsistent casing for the resource group name in the 'id' field when query the resources with type Microsoft.CognitiveServices/accounts

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/main/specification/resourcegraph/resource-manager/Microsoft.ResourceGraph/stable/2024-04-01/resourcegraph.json#L37

### API Spec version

2024-04-01

### Describe the bug

The casing of the 'id' field is being inconsistently returned when query the resources with type Microsoft.CognitiveServices/accounts with Resource Graph API, when it contains upper case letters.
For example, using a resource group named 'BA-Test', firstly the 'id' field is returned with this in mixed case (/resourceGroups/BA-Test/) and after deploy a model in the AI Service, it would become lower case (/resourceGroups/ba-test/).

### Expected behavior

Response to have consistent casing for the resource group in the 'id' field, every time, preferably the mixed casing to match the console.

### Actual behavior

Resource group name in the 'id' field in the response would turn into lower case once deploy a model in the AI Service and turn back to mixed case once the deployed model removed.

### Reproduction Steps

API: https://learn.microsoft.com/en-us/rest/api/azureresourcegraph/resourcegraph/resources/resources?view=rest-azureresourcegraph-resourcegraph-2024-04-01
Request body: `"query": "Resources | project id, name, type, resourceGroup | where type =~ 'Microsoft.CognitiveServices/accounts'"`
Steps:

1. Create an Azure AI Services resource in the console using a mixed case resource group (for example BA-Test)

2. Call the api and the print out for the relevant resource will (most likely) be:
> /subscriptions/my-sub-id/resourceGroups/BA-Test/providers/Microsoft.CognitiveServices/accounts/casing-test
> ba-test

3. Navigate to AI Studio from this resource and deploy a model (i used gpt-4). Then call the api with same body and response is likely to be:
> /subscriptions/my-sub-id/resourceGroups/ba-test/providers/Microsoft.CognitiveServices/accounts/casing-test
> ba-test

### Environment

_No response_

Start with specification/resourcegraph/resource-manager/Microsoft.ResourceGraph/stable/2024-04-01/resourcegraph.json at the referenced line, then reproduce the query through the Resource Graph API endpoint before and after deploying a model. Compare the resource ID casing in both responses; done means the issue's expected consistent resource-group casing is addressed or the required specification change is clearly identified.

Written by the indexing model from the issue text.