[RFE] deprecate "hash_distribution_replicas" config option

[Yuriy Zveryanskyy]

This is experimental feature, number of hosts to map onto each hash partition.
Setting it more than 1 causes couple of bugs:
1) Probability of slow running of periodical task if exclusive locking is needed.
2) Double sending of sensors data if it enabled.
3) Create configuration for netboot on >1 conductors, only one can be cleaned via ironic api.
4) If conductor dead with enabled console and active conductors >1 console processes
tries to start on "hash_distribution_replicas" conductors, we will not predict where it
will be started and there is a possibility that processes can't be stopped because API
use only one conductor for routing.

[Jay Faulkner (jason-oldos)]

I'm +2 to this being approved.

[Ruby Loo (rloo)]

I'm good with approving this too. Since it is deprecating, I'll bring it up in our meeting if I remember...

[Ruby Loo (rloo)]

This was discussed in the ironic meeting [1] and we agreed that this should be deprecated.

[1] http://eavesdrop.openstack.org/meetings/ironic/2017/ironic.2017-11-20-17.00.log.html#l-199