Hive janitor does not properly clean up / generate statistics

[jkarder]

On the one hand, some queries executed by the janitor time out. On the other hand, it seems as if the FILESTREAM garbage collector does not run, which leaves us with a huge amount of data which is no longer referenced by any row.

Note: GC can be forced via sp_filestream_force_garbage_collection.

[jkarder]

r17574: overhauled statistics generation and cleanup

• switched to a single thread for database cleanup and statistics generation (executed sequentially)
• switched to preemptive deletion of items that are in status DeletionPending (for jobs: statelogs, taskdata, tasks)
• added code that aborts tasks whose jobs have already been marked for deletion
• added method UseTransactionAndSubmit in addition to UseTransaction in PersistenceManager
• updated DAO methods and introduced more bare metal sql
• introduced DAO methods for batch deletion
• fixed usage of enum values in DAO sql queries
• deleted unnecessary triggers tr_JobDeleteCascade and tr_TaskDeleteCascade in Prepare Hive Database.sql
• changed scheduling for less interference with janitor and other heartbeats
  • increased scheduling patience from 20 to 70 seconds (to wait longer to get the mutex for scheduling)
  • changed signature of ITaskScheduler.Schedule
  • added base class for TaskSchedulers and moved assignment of tasks to slaves into it
  • changed RoundRobinTaskScheduler to use bare metal sql
• made MessageContainer a storable type (leftover)
• updated HiveJanitorServiceInstaller.nsi