Azure SQL database provisioning after initial deployment

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Describe the bug

I have seen related issues https://github.com/dotnet/aspire/issues/3101

but this doesn't actually indicate where the issue is fixed.

I have this provisioning code:

```
var az = builder.AddAzureSqlServer("sqlserver")
.ConfigureInfrastructure(infra =>
{
var azureResources = infra.GetProvisionableResources();
var azureDb = azureResources.OfType().Single();
azureDb.Sku = new SqlSku() { Name = "GP_S_Gen5_1" };
});

var db = az.AddDatabase("db");
app.WithReference(db).WaitFor(db);
```

which worked when I initially published. Some time later I added a redis instance to the orchestration. I assume this triggered provisioning again, because I suddenly got failure message on Publish related to the SQL resources.

I established that using .RunAsExisting() on az would use the existing instance of the SQL Server.

However the AddDatabase call still fails and despite some searching, I can't find the correct way to configure a similar "use existing" implementation.

The provisioning logic is not obvious to me. I have seen CosmosDB / and Az Table storage publish in an idempotent fashion, without the UseExisting
semantics.

Aspire and package versions as below:

```

Exe
net8.0
enable
enable

9078373a-0567-401e-90e7-7c7415112564

```

### Expected Behavior

_No response_

### Steps To Reproduce

_No response_

### Exceptions (if any)

None

### .NET Version info

.Net 8

### Anything else?

I'm using VS 2022 - aspire publish

Aspire and package versions as below:

```

Exe
net8.0
enable
enable

9078373a-0567-401e-90e7-7c7415112564

```