DEV: Increase process_post lock timeout

The process_post job uses CookedPostProcessor which also uses a
DistributedMutex. There's no good reason for the timeout of the outer
lock to be smaller than the timeout of the inner lock.

app/jobs/regular/process_post.rb

@@ -7,7 +7,7 @@ module Jobs
   class ProcessPost < ::Jobs::Base
 
     def execute(args)
-      DistributedMutex.synchronize("process_post_#{args[:post_id]}") do
+      DistributedMutex.synchronize("process_post_#{args[:post_id]}", validity: 10.minutes) do
         post = Post.find_by(id: args[:post_id])
         # two levels of deletion
         return unless post.present? && post.topic.present?