Clear shell process log before restart

Report regeneration and upload tasks add a lot of logs
Since we dont clear logs on every regeneration we have
too much outdated logs. This commit wil change that
and clear logs before ruinning the report..

lib/foreman_inventory_upload/async/shell_process.rb

@@ -7,6 +7,7 @@ class ShellProcess < ::Actions::EntryAction
       include ::ForemanRhCloud::Async::ExponentialBackoff
 
       def plan(instance_label, more_inputs = {})
+        clear_task_output(instance_label)
         inputs = more_inputs.merge(instance_label: instance_label)
         plan_self(inputs)
       end
@@ -53,6 +54,11 @@ def rescue_strategy_for_self
         Dynflow::Action::Rescue::Fail
       end
 
+      def clear_task_output(label)
+        TaskOutputLine.where(label: label).delete_all
+        TaskOutputStatus.where(label: label).delete_all
+      end
+
       private
 
       def preprocess_command(command)