The custom repositories action is using the `no_rhsm` option to identify if we should check for custom repositories availability or not. While this is not a bad option, we want to make sure that if the user specifies a custom repository, we will try to check it anyhow.

This issue ask for a change in the code where we will be able to check it every time a user uses a custom repository.

Acceptance Criteria

• Use `enablerepo` instead of `no_rhsm` to check custom repository availability
• Make it a dependency of `SUBSCRIBE_SYSTEM` to be sure that we are checking the repos after we subscribe.