BACKUP previous set up triggers using DICT.
This lead to all kind of trouble.
An smaller alternative to using SUMA for backup
  is to just make BACKUP handle triggers to TUP directly.

This way all triggers will be totally local,
  and error handling is much simpler.

--- old impl.

Start: Master recives GSN_DEFINE_BACKUP_CONF from all participants
Master sends CREATE_TRIG_REQ for all tables to local DICT (dict master)
Master sends START_BACKUP_REQ to all paricipants with trigger ids from DICT
Master sends ALTER_TRIG_REQ (online) to local DICT
Master waits for GCP
Master starts distributed scan
When scan has finished
Master waits for GCP
Master sends DROP_TRIGGER to local DICT
Master sends STOP_BACKUP_REQ to all participants

--- new impl.

Start: Master recives GSN_DEFINE_BACKUP_CONF from all participants
Master sends START_BACKUP_REQ to all paricipants
  Participand sends CREATE_TRIG_REQ for all tables to local TUP
Master waits for GCP
Master starts distributed scan
When scan has finished
Master waits for GCP
Master sends STOP_BACKUP_REQ to all participants
  Participant sends DROP_TRIGGER to local TUP

Changes:
All trigger handling is _local_
 This implies, that abort (e.g due to node failure) can be _local_


fix testBackup test so that it will run successfully with the (now correct)
backup trigger code.