After doing more searching on the internet, it looks like “force_post_sync_actions” is now depreciated and has been replaced with “–skip-metadata-check”
https://bugzilla.redhat.com/show_bug.cgi?id=1498560
https://projects.theforeman.org/issues/23033
If you are following this guide, skip that step and modify the next command to:
hammer repository synchronize --skip-metadata-check true --name “base_x86_64” --product “el7_repos”
This should run for you.