Set max_microversion for placement and volume

Set max_microversion for placement and volume

It sets max_microversion to latest because if both values are not
specified, Tempest avoids tests which require a microversion [1].

It completes the previous change about nova [2].

[1] https://docs.openstack.org/tempest/latest/sampleconf.html
[2] https://gerrit.opnfv.org/gerrit/#/c/67318/

Change-Id: Ieab56a239077476dd9a0e1ee97ac4293c4075f5c
Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
(cherry picked from commit b9048a25355e1d6c29c84ca10a3d859841468f50)