SSHManager.update_connection: add possibility to open new connection with
parameters, if no connection presents.
This testgroup should be run with this parameters:
export MULTIPATH=True
export SLAVE_MULTIPATH_DISKS_COUNT=2
export MULTIPATH_TEMPLATE=system_test/tests_templates/tests_configs/multipath_3_nodes.yaml
Implements: blueprint test-multipath-devices
Change-Id: I73ffc4338b59c8b44eabe27b2d759b7fbbba19a4
d8f7b0d221