Change ssh_utils parameter to correctly sends keepalive packets
Change ssh_utils parameter to correctly sends keepalive packets

The current implementation of ssh_utils never sends keepalive packets.
In ssh_utils.SSHPool, the socket timeout parameter is set to None
intending to keep ssh connections open.
However, when the parameter is set to None, ssh_utils does not run the
code to compare idle duration and keepalive interval.

This patch reverts the socket timeout parameter to default (0.1 sec).
The ssh_utils compares them every 0.1 seconds, and sends a keepalive
packet if idle duration > keepalive interval (= self.conn_timeout).

Change-Id: I8234083107207b9ebc0849947e8de92b5cf3e36e
Closes-Bug: #1673662

Datera/cinder,openstack/cinder,j-griffith/cinder,mahak/cinder,phenoxim/cinder,mahak/cinder,openstack/cinder,Datera/cinder,j-griffith/cinder,phenoxim/cinder