CI: Fail if foreman db cannot be dropped

This will lead to followup errors, so we shouldn't swallow the error.
This command is supposed to pass always.

Author: bastelfreak

spec/support/acceptance/purge.rb

@@ -10,5 +10,5 @@ def purge_foreman
 
   apache_service_name = ['debian', 'ubuntu'].include?(os[:family]) ? 'apache2' : 'httpd'
   on default, "systemctl stop #{apache_service_name} dynflow-sidekiq@* foreman foreman-proxy", { :acceptable_exit_codes => [0, 5] }
-  on default, 'runuser - postgres -c "dropdb --force foreman"', { :acceptable_exit_codes => [0, 1, 127] }
+  on default, 'runuser - postgres -c "dropdb --if-exists --force foreman"', { :acceptable_exit_codes => [0] }
 end