Synapse Linked Service Creation Error

The `2021-06-01-preview` for Synapse Linked Service returns response code 200 during create/update though the resource actually fails due to a bad payload. You can test this by passing in a bad `type` into the payload:

```
{
"properties": {
"type": "LinkedService",
"typeProperties": {
"connectionString": "someconnectionstring"
}
}
}
```

The API will report this as `200` even though it's a bad request and should return `400`

Locate the Synapse Linked Service specification for the 2021-06-01-preview API and reproduce the create/update request with the invalid type payload shown in the issue. Inspect how the response status is defined, and consider the issue done when that invalid payload returns 400 instead of 200 while valid requests retain their expected response.

Written by the indexing model from the issue text.