Currently, `GetVolumeGroup()` fetches the RBD group from the
pool using the clusterID & poolID encoded in the VolumeGroupHandle.
However, this approach may fail in a secondary mirrored cluster,
where the clusterID & poolID could differ.
This commit ensures that `GetVolumeGroup` leverages the
clusterIDMapping and RBDPoolIDMapping to locate the RBD group in the
appropriate pool if it is not found in the pool corresponding
to the poolID encoded in the VolumeGroupHandle.
Signed-off-by: Praveen M <m.praveen@ibm.com>
e4d41c42d6