[accounts][migrations] clean up unused migration

This migration was used to shift registered users to the new supervision
ecosystem.

Fixes #569
1 job for 569_proper_cleanup_account_supervision_check_migration in 16 minutes and 52 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Build
passed #209970
docker-build
build_linux_36

00:16:52

69.0%