Allow migration cli to work ignoring historically misnamed scripts

Historic files are present in our sql modules which cannot be executed by the migration
cli (without complicating too much the code). So simply ignore those when listing the
files to execute. That will stop making the cli refuse to work on some modules (e.g.
scheduler and its 30-bis.sql script).

Refs. swh/infra/sysadm-environment#4933