Deprecate volume api selection config option

Tempest volume tests can be run against v2 or v3
API based on config option ``CONF.volume.catalog_type``.
If catalog_type is ``volumev2``, then all the volume
tests will run against v2 API. If catalog_type is
``volumev3`` which is default in Tempest, then all the volume
tests will run against v3 API.

That makes below config option unusable in Tempest which used to
select the target volume API for volume tests.

    * ``CONF.volume-feature-enabled.api_v2``
    * ``CONF.volume-feature-enabled.api_v3``

This commit deprecate them and marked for removal in future.
Change-Id: Ifed9d9e77e37bb846be724a8d2245f130aae02c7
2 files changed