Delivery Properties are deleted when enabling DQL on eventgrid subscription

### Describe the bug

I create a custom topic, create a webhook eventgrid subscription, I added 2 delivery properties.

But when I use az eventgrid event-subscription update to enable DQL on the eventgrid, those delivery properties got deleted.

### Related command

az eventgrid event-subscription update --name test2 --source-resource-id "/subscriptions/****a77a2c76a66c/resourceGroups/test/providers/Microsoft.EventGrid/topics/topic0927" --deadletter-identity-endpoint "/subscriptions/****a77a2c76a66c/resourceGroups/search/providers/Microsoft.Storage/storageAccounts/****/blobServices/default/containers/event-grid" --deadletter-identity systemassigned --endpoint "https://***.azurewebsites.net/api/updates"

### Errors

delivery properties got deleted.

### Issue script & Debug output

msal.telemetry: Generate or reuse correlation_id: 8a21392f-4645-40a5-908c-a125d1359700
cli.azure.cli.core.sdk.policies: Request URL: 'https://management.azure.com/subscriptions/********a77a2c76a66c/resourceGroups/test/providers/Microsoft.EventGrid/topics/topic0927/providers/Microsoft.EventGrid/eventSubscriptions/test2?api-version=2021-10-15-preview'
cli.azure.cli.core.sdk.policies: Request method: 'PATCH'
cli.azure.cli.core.sdk.policies: Request headers:
cli.azure.cli.core.sdk.policies: 'Content-Type': 'application/json'
cli.azure.cli.core.sdk.policies: 'Content-Length': '959'
cli.azure.cli.core.sdk.policies: 'Accept': 'application/json'
cli.azure.cli.core.sdk.policies: 'x-ms-client-request-id': '8ac67e13-8495-11ef-87b3-010101010000'
cli.azure.cli.core.sdk.policies: 'CommandName': 'eventgrid event-subscription update'
cli.azure.cli.core.sdk.policies: 'ParameterSetName': '--name --source-resource-id --deadletter-identity-endpoint --deadletter-identity --endpoint --delivery-attribute-mapping --delivery-attribute-mapping --debug'
cli.azure.cli.core.sdk.policies: 'User-Agent': 'AZURECLI/2.55.0 (MSI) azsdk-python-mgmt-eventgrid/10.2.0b2 Python/3.11.5 (Windows-10-10.0.26100-SP0)'
cli.azure.cli.core.sdk.policies: 'Authorization': '*****'
cli.azure.cli.core.sdk.policies: Request body:
cli.azure.cli.core.sdk.policies: {"destination": {"endpointType": "WebHook", "properties": {"endpointUrl": "https://***.azurewebsites.net/api/updates", "maxEventsPerBatch": 1, "preferredBatchSizeInKilobytes": 64, "deliveryAttributeMappings": [{"name": "test", "type": "Static", "properties": {"value": "value", "isSecret": true}}, {"name": "test2", "type": "Static", "properties": {"value": "value2", "isSecret": true}}]}}, "filter": {"subjectBeginsWith": "", "subjectEndsWith": "", "enableAdvancedFilteringOnArrays": true}, "eventDeliverySchema": "EventGridSchema", "retryPolicy": {"maxDeliveryAttempts": 30, "eventTimeToLiveInMinutes": 1440}, "deadLetterWithResourceIdentity": {"identity": {"type": "SystemAssigned"}, "deadLetterDestination": {"endpointType": "StorageBlob", "properties": {"resourceId": "/subscriptions/*******b-a77a2c76a66c/resourceGroups/search/providers/Microsoft.Storage/storageAccounts/****", "blobContainerName": "event-grid"}}}}
urllib3.connectionpool: Starting new HTTPS connection (1): management.azure.com:443
urllib3.connectionpool: https://management.azure.com:443 "PATCH /subscriptions/*****a77a2c76a66c/resourceGroups/test/providers/Microsoft.EventGrid/topics/topic0927/providers/Microsoft.EventGrid/eventSubscriptions/test2?api-version=2021-10-15-preview HTTP/1.1" 201 1378
cli.azure.cli.core.sdk.policies: Response status: 201
cli.azure.cli.core.sdk.policies: Response headers:
cli.azure.cli.core.sdk.policies: 'Cache-Control': 'no-cache'
cli.azure.cli.core.sdk.policies: 'Pragma': 'no-cache'
cli.azure.cli.core.sdk.policies: 'Content-Length': '1378'
cli.azure.cli.core.sdk.policies: 'Content-Type': 'application/json; charset=utf-8'
cli.azure.cli.core.sdk.policies: 'Expires': '-1'
cli.azure.cli.core.sdk.policies: 'Retry-After': '10'
cli.azure.cli.core.sdk.policies: 'Strict-Transport-Security': 'max-age=31536000; includeSubDomains'

### Expected behavior

in PATCH request, those attributes need to be preserved.

### Environment Summary

azure-cli 2.65.0

core 2.65.0
telemetry 1.1.0

Extensions:
ai-examples 0.2.5
ml 2.30.1
ssh 2.0.5

Dependencies:
msal 1.31.0
azure-mgmt-resource 23.1.1

### Additional context

_No response_