Microsoft.Security/governanceRules API not idempotent

Hi,

This is linked to the following issue: https://github.com/Azure/bicep-types-az/issues/1664#event-9605619956

I can create a new Azure Defender For Cloud Governance rule via Bicep (see API call issue above).

If the same IaC is executed a second time, I get the error

```
[{"code":"GovernanceRulePriorityConflict","message":"Rule priority 1 already exist"}
```
As name of the resource I specify the following parameter:
```
param highGovRoleGuid string = newGuid()
```
Can you make the necessary adjustments to the REST API so that the same code can un twice without error?

Start with the linked bicep-types-az issue and reproduce the reported Azure Defender for Cloud governance-rule deployment twice using the shown newGuid parameter. Trace the Microsoft.Security/governanceRules REST behavior around the GovernanceRulePriorityConflict response; done means the same IaC can run again without that error.

Written by the indexing model from the issue text.