Stupid network name ruins the default network on migration

[Thorinwasher]

Bug Description

Migrating when networks of the name <@default@> makes it impossible to use the default network

Reproduction Steps

• Make a portal in the network <@default@> on a legacy stargate instance
• Migrate to latest Stargate version
• Try to create a portal on the default network

Desired Behaviour

The network id <@default@> should be protected during migrations. One possible solution is to simply just make the ID unwritable in legacy by adding a : character

Observed Behaviour

It's nomore possible to create a default network, as that id is used by the custom network <@default@>

Trace Logs

No response

Other Information

No response