ASC_Storage_DisallowPublicBlobAccess_Audit: Duplicate 'effects' parameter in policy definition

## ISSUE TITLE:
ASC_Storage_DisallowPublicBlobAccess_Audit: [Bug] Duplicate 'effects' parameter

## ISSUE DESCRIPTION:
Policy: https://github.com/Azure/azure-policy/blob/master/built-in-policies/policyDefinitions/Storage/ASC_Storage_DisallowPublicBlobAccess_Audit.json

The policy lists duplicate 'effects' as possible parameter values.

**Expected**
Duplicates should be removed, consistent with other built in policies.

**Actual**
Duplicate effects are listed.

**Note**
It seems that the schema only supports low case values, but built-in policys typically use an uppercase first letter:
https://schema.management.azure.com/schemas/2020-10-01/policyDefinition.json

It is not possible to save a policy in Azure Portal with uppercase effect name:

Open built-in-policies/policyDefinitions/Storage/ASC_Storage_DisallowPublicBlobAccess_Audit.json and inspect the effects parameter values. Compare its allowed values with nearby built-in policies and the referenced policy-definition schema. Done means the duplicate effect entry is removed and the remaining values follow the repository's established casing and schema expectations.

Written by the indexing model from the issue text.