Always removed last added partitions from overloaded members.
This should decrease overall no. of migrations during repartitiong.
If a member is detected as dead a repartitioning thread on a master is paused and
its re-activation is scheduled. Other members have time to notice the member
is dead, so they can promote backups and shift partition tables.

When another member is detected as dead while the migration thread is still paused
the original re-activation is now postponed.
MAX_NO_MASTER_CONFIRMATION_SECONDS increased to 500s.

It decrease a chance of data loss when multiple members are running on the same host which dies suddenly.

There are two commonly used mechanisms to detect dead members:
 - heartbeats
 - master confirmation

By increasing the MAX_NO_MASTER_CONFIRMATION_SECONDS we make sure the dead node is always detected by
the heartbeat mechanism. Heartbeats are sent with higher frequency than the master confirmations so there
is a good chance we detect all dead members before re-partitioning process is started.
unused code removed
unused argument removed
Merge pull request #3433 from jerrinot/fix/dataloss/master

The Dataloss Race Condition fixed