[BUG] `Microsoft.MachineLearningServices` @ `2024-04-01` - casing in user assigned identity in encryption for workspaces is not preserved

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/262a9d16d94c3448fc7f37c840757f6e74acf7de/specification/machinelearningservices/resource-manager/Microsoft.MachineLearningServices/stable/2024-04-01/machineLearningServices.json#L5135

### API Spec version

2024-04-01

### Describe the bug

The API returns all ID segments for the user assigned identity ID for encryption in lower case:

`PUT`:
```
...
"encryption": {
"identity": {
"userAssignedIdentity": "/subscriptions/***/resourceGroups/acctestRG-aiservices-240918114038029797/providers/Microsoft.ManagedIdentity/userAssignedIdentities/acctestuai-240918114038029797"
},
...
```

`GET`:
```
"encryption": {
"status": "Enabled",
"identity": {
"userAssignedIdentity": "/subscriptions/1a6092a6-137e-4025-9a7c-ef77f76f2c02/resourcegroups/acctestrg-aiservices-240918114038029797/providers/microsoft.managedidentity/userassignedidentities/acctestuai-240918114038029797"
},
```

### Expected behavior

The API preserves the casing in the user specified segments.

### Actual behavior

The API does not preserve the casing in the user specified segments.

The resource group name in the segment was sent with `acctestRG-aiservices-240918114038029797` but returned `acctestrg-aiservices-240918114038029797`

### Reproduction Steps

Provision an AI services hub with encryption using a user assigned identity with upper and lower casing in the ID segments.

### Environment

_No response_