Current RBD code is incorrectly reporting the stats of the pool in the
following ways:
- `provisioned_capacity_gb` contains physical space used by cinder created
volumes.
- `free_capacity_gb` is not taking into account that pools can have quota
restrictions and they should be used as the reference for the free capacity.
- `total_capacity` dynamically changes, which means that there is no way to
have a fixed over provisioning capacity.
This patch fixes the stats reporting making sure we return the right
values in `provisioned_capacity_gb` and `free_capacity_gb`, and allows
us to use a static calculation of the `total_capacity` using
`report_dynamic_total_capacity` configuration option.
We don't report `allocated_capacity_gb` because this is something that
is calculated by the Cinder core code and should not be reported by
drivers, even if it's not currently working as expected [1][2].
[1] https://bugs.launchpad.net/cinder/+bug/1712549
[2] https://bugs.launchpad.net/cinder/+bug/1706057
Change-Id: I1e82bf9d0b6cc0fb1d1fc2dd8b8ccc59aea3f73f
Closes-Bug: #1706060
8469109016