Azure PowerShell: For `New-AzGalleryImageDefinition`, `'TrustedLaunch'` and `'TrustedLaunchSupported'` aren't synonyms

I tried to take advantage of https://github.com/Azure/azure-powershell/pull/24869 in Azure PowerShell 12.0.0 by changing

https://github.com/microsoft/STL/blob/63354c3fa9c1fb2ab1fccb58c47d23c6af1c290f/azure-devops/create-1es-hosted-pool.ps1#L294-L305

to omit -Feature @(@{ Name = 'SecurityType'; Value = 'TrustedLaunch'; }) and -HyperVGeneration 'V2'. This caused the following command

https://github.com/microsoft/STL/blob/63354c3fa9c1fb2ab1fccb58c47d23c6af1c290f/azure-devops/create-1es-hosted-pool.ps1#L311-L317

to fail with

New-AzGalleryImageVersion: C:\GitHub\STL\azure-devops\create-1es-hosted-pool.ps1:279
Line |
 279 |  $ImageVersion = New-AzGalleryImageVersion `
     |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~
     | The security type 'TrustedLaunchSupported' is not supported for the source id ''. Currently only Vhd Blob, User
     | Image and Gallery Image Version sources are supported for 'TrustedLaunchSupported' images. ErrorCode:
     | InvalidParameter ErrorMessage: The security type 'TrustedLaunchSupported' is not supported for the source id ''.
     | Currently only Vhd Blob, User Image and Gallery Image Version sources are supported for 'TrustedLaunchSupported'
     | images. ErrorTarget: galleryImageVersion.properties.storageProfile.osDiskImage.source.id StatusCode: 400
     | ReasonPhrase: Bad Request OperationID : 352dcb67-3fe5-4a4b-98ba-640efe5ecd0f

It appears that the new default of 'TrustedLaunchSupported' is not a synonym for 'TrustedLaunch'.

We should report this upstream, but we'll need to distill our script into a self-contained repro. I'm a lazy kitty, so I'll do this later. 🐈

Start with azure-devops/create-1es-hosted-pool.ps1 around the referenced lines 294-317 and reproduce the failure using New-AzGalleryImageDefinition and New-AzGalleryImageVersion. Distill the existing script into a self-contained reproduction that demonstrates the difference between TrustedLaunch and TrustedLaunchSupported, then report it upstream.