[BUG] activity log alerts default to enabled: false instead of true

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/main/specification/monitor/resource-manager/Microsoft.Insights/stable/2020-10-01/activityLogAlerts_API.json

### API Spec version

2020-10-01

### Describe the bug

https://learn.microsoft.com/en-us/rest/api/monitor/activity-log-alerts/create-or-update?view=rest-monitor-2020-10-01&tabs=HTTP&tryIt=true#activitylogalertresource

The docs say it should default to `enabled: true` reality is it defaults to `enabled: false`

### Expected behavior

enabled: true

### Actual behavior

enabled: false

### Reproduction Steps

minimal example:
```
{
"location": "Global",
"properties": {
"scopes": [
"/subscriptions/subscription_id/resourceGroups/resource_group"
],
"condition": {
"allOf": [
{
"field": "category",
"equals": "Administrative"
},
{
"field": "level",
"equals": "Error"
}
]
},
"actions": {
"actionGroups": [
{
"actionGroupId": "/subscriptions/subscription_id/resourceGroups/resource_group/providers/microsoft.insights/actionGroups/Monitoring-e-resource_group-ActionGroup"
}
]
}
}
}
```

See #35342 on why I also set the "optional" location parameter in a minimal example

### Environment

direct rest api access

Start with the linked activityLogAlerts_API.json specification and compare its enabled property with the linked Microsoft REST API documentation. Reproduce the minimal request through direct REST API access and verify whether the default is true or false. Done means the specification and documented behavior accurately reflect the service behavior.

Written by the indexing model from the issue text.