[Non-Backfill Approach] Add a temporary column with default value of 1 and then rename

• Include SafelyChangeColumnDefault as per this guide: https://docs.gitlab.com/development/database/avoiding_downtime_in_migrations/#changing-column-defaults
• Post deployment migration:

transaction do
    add a column organization_id_tmp default 1 not null
    drop organization_id
    rename organization_id_tmp to organization_id
end

• Re-add FK and unique index