Running the `foreman-rake katello:clean_backend_objects` script fails with a 'Not all the services have been started. Check the status report above and try again.' error

Issue

Running the foreman-rake katello:clean_backend_objects script fails:

# foreman-rake katello:clean_backend_objects
'ErbParser' is ignored.
'RubyParser' is ignored.
API controllers newer than Apipie cache! Run apipie:cache rake task to regenerate cache.
{:services=>
  {:candlepin=>{:status=>"ok", :duration_ms=>"162"},
   :candlepin_auth=>{:status=>"ok", :duration_ms=>"44"},
   :foreman_tasks=>{:status=>"ok", :duration_ms=>"3"},
   :katello_events=>
    {:status=>"FAIL", :message=>"Not running", :duration_ms=>"1"},
   :candlepin_events=>
    {:status=>"FAIL", :message=>"Not running", :duration_ms=>"0"},
   :pulp3=>{:status=>"ok", :duration_ms=>"347"},
   :pulp3_content=>{:status=>"ok", :duration_ms=>"322"}},
 :status=>"FAIL"}
rake aborted!
Not all the services have been started. Check the status report above and try again.
/opt/theforeman/tfm/root/usr/share/gems/gems/katello-4.1.1.60/lib/katello/tasks/reimport.rake:10:in `block (2 levels) in <top (required)>'
/opt/rh/rh-ruby27/root/usr/share/gems/gems/rake-13.0.1/exe/rake:27:in `<top (required)>'
Tasks: TOP => katello:clean_backend_objects => katello:check_ping
(See full trace by running task with --trace)