FIX: stop using Rails connection reaper in multisite

The Rails 5.2 connection reaper appears to be leaking threads
this is a quick fix to stop it, though we need to make sure we
never leak connection pools as well.

config/application.rb

@@ -270,5 +270,9 @@ module Discourse
       g.test_framework :rspec, fixture: false
     end
 
+    # we have a monkey_patch we need to require early... prior to connection
+    # init
+    require 'freedom_patches/reaper'
+
   end
 end

lib/freedom_patches/reaper.rb

@@ -0,0 +1,18 @@
+# Discourse ships with a connection reaper
+# this patch ensures that the connection reaper never runs in Rails
+#
+# In Rails 5.2 the connection reaper is "per-pool" this means it can bloat
+# threads quite a lot in a multisite
+#
+# Note, the "correct" way is to set this in the spec, however due to multisite
+# getting reaper_interval=0 into all the specs is not going to be trivial
+# when we eventually do that we can remove this patch
+
+if !defined? ActiveRecord::ConnectionAdapters::ConnectionPool::Reaper
+  raise "Can not find connection Reaper class, this patch will no longer work!"
+end
+
+class ActiveRecord::ConnectionAdapters::ConnectionPool::Reaper
+  def run
+  end
+end