[Birthday 1.0.4] Grab the config instance instead of json

[flaree]

Grabs the config instance of Birthdays, init the custom group then migrate.

There's a del in there as there was a backup key made when he switched to custom groups.

[Vexed01]

Let's ignore the cog load check, that seems like it's a workflow I need to stop on PRs as it doesn't work for token escalation etc.