Foreman Maintain

Right now in https://github.com/theforeman/foreman_maintain/blob/master/lib/foreman_maintain/package_manager/yum.rb#L70-L73 we only consider exit code 100 as the code_of_success.

But if no package updates are available, Then satellite-maintain fails the check-update step as the exit code, in this case, would be 0.

If no package updates are present and the exit code from yum is 0, then also the check-update action should pass as a successful execution.