remove supported region and update NSG template (#52399)

Co-authored-by: Felicity Chapman <felicitymay@github.com>

Author: Steve-Glass

data/reusables/actions/azure-vnet-procedures-prereqs.md

@@ -213,18 +213,6 @@ You will use a script to automate configuring your Azure resources.
  destinationAddressPrefixes: []
  }
  }
- {
- name: 'DenyInternetOutBoundOverwrite'
- properties: {
- protocol: '*'
- sourcePortRange: '*'
- destinationPortRange: '*'
- sourceAddressPrefix: '*'
- destinationAddressPrefix: 'Internet'
- access: 'Deny'
- priority: 400
- direction: 'Outbound'
- }
  }
  ]
  }

data/reusables/actions/azure-vnet-supported-regions.md

@@ -7,7 +7,6 @@ The {% data variables.product.prodname_actions %} service supports a subset of a
 <li><code>WestUs3</code></li>
 <li><code>CentralUs</code></li>
 <li><code>NorthCentralUs</code></li>
-<li><code>SouthCentralUs</code></li>
 <li><code>AustraliaEast</code></li>
 <li><code>JapanEast</code></li>
 <li><code>FranceCentral</code></li>
@@ -25,7 +24,6 @@ Azure private networking supports GPU runners in the following regions.
 * `EastUs`
 * `WestUs`
 * `NorthCentralUs`
-* `SouthCentralUs`
 
 Azure private networking supports arm64 runners in the following regions.
 
@@ -34,6 +32,5 @@ Azure private networking supports arm64 runners in the following regions.
 * `WestUs2`
 * `WestUs3`
 * `NorthCentralUs`
-* `SouthCentralUs`
 
 If your desired region is not supported, please submit a request for new region availability in [this GitHub form](https://resources.github.com/private-networking-for-github-hosted-runners-with-azure-virtual-networks/). You may also use global virtual network peering to connect virtual networks across Azure regions. For more information, see [Virtual network peering](https://learn.microsoft.com/en-us/azure/virtual-network/virtual-network-peering-overview) in the Azure documentation.