Remove deprecated config options for volume API selection

Volume APIs tests have been moved to v3 as default and can be run
under v2 API via catalog_type.
- https://review.opendev.org/#/q/topic:volume-default-testing-v3+(status:open+OR+status:merged)

Below config options were deprecated since Rocky and now time to remove them:
    * ``CONF.volume-feature-enabled.api_v2``
    * ``CONF.volume-feature-enabled.api_v3``

Change-Id: I31f487694e5f5e586f99323c81e45f43306606fb
6 files changed