Should portal migration work between Developer SKU and StandardV2 Sku?

## Bug description

I am unable to import the developer portal content from an APIM service of Developer Sku to one of Standardv2 sku.

The help article here: https://learn.microsoft.com/en-us/azure/api-management/automate-portal-deployments
Suggests that StandardV2 is a supported Sku.

If I run the migrate v3 script between two developer skus I get:
```
api-management-developer-portal\scripts.v3> node ./migrate --sourceSubscriptionId "xxx" --sourceResourceGroupName "xxx" --sourceServiceName "xxx" --destSubscriptionId "yyy" --destResourceGroupName "yyy" --destServiceName "yyy"
Exporting...
Cleaning up...
Importing...
DONE
```
When running between Developer Sku -> StandardV2 Sku I get:
```
api-management-developer-portal\scripts.v3> node ./migrate --sourceSubscriptionId "xxx" --sourceResourceGroupName "xxx" --sourceServiceName "xxx" --destSubscriptionId "yyy" --destResourceGroupName "yyy" --destServiceName "yyy"
Exporting...
Cleaning up...
Unable to complete migration. Unable to complete cleanup. Unable to delete media files. Could not complete request to https://management.azure.com/subscriptions/yyy/resourceGroups/yyy/providers/Microsoft.ApiManagement/service/yyy/portalSettings/mediaContent/listSecrets?api-version=2021-08-01. Status: 400 Bad Request
```

## Reproduction steps

Create a Developer Sku APIM instance
Create a StandardV2 Instance
run migrate v3 from one to the other

## Expected behavior

I would expect this to work or a message on the help page to say that this isn't supported.

## Is self-hosted portal?

No

## API Management service name

lantern-test-apim

Start with the scripts.v3 migrate entry point and reproduce the documented command between Developer and StandardV2 APIM services. Trace the cleanup failure at portalSettings/mediaContent/listSecrets, then compare it with a Developer-to-Developer migration. Done means the migration succeeds for the SKU pair or the help article clearly documents that the combination is unsupported.

Written by the indexing model from the issue text.