Shrink Tempest scenario manager copy
Shrink Tempest scenario manager copy

scenario manager in tempest plugin was copied from
Tempest to avoid any plugin break.

This copied version of scenario manager is using lot of
Tempest interfaces. Many of them are not stable and might
change which can break plugin.

For example - https://review.openstack.org/#/c/503875/3

This commit shrinks the scenario manager copy to keep
only required methods.

Change-Id: I95385f8359521bd8baa603cdcc3f0b6ca4c81db8

openstack/octavia,openstack/octavia,openstack/octavia