Replace deprecated log api test with up-to-date version
Replace deprecated log api test with up-to-date version

This version use only monasca devstack plugin with option to install old log api.

Remove python2 tempest test.

Depends-On: https://review.opendev.org/#/c/718512/
Change-Id: Ie21a34260ad16dcdd1592762da2942c6eeeccfae

stackforge/monasca-log-api,openstack/monasca-log-api,openstack/monasca-log-api,stackforge/monasca-log-api,stackforge/monasca-log-api,openstack/monasca-log-api