Moved to add scheduling to the promote
operation as scheduling need to be added
when the image is promoted and this is
the correct method of adding the scheduling
to make the scheduling take place.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

added helper function to get the cluster ID.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

currently we have a bug in rbd mirror scheduling module.
After doing failover and failback the scheduling is not
getting updated and the mirroring snapshots are not
getting created periodically as per the scheduling
interval. This PR workarounds this one by doing below
operations

* Create a dummy (unique) image per cluster and this image
should be easily identified.

* During Promote operation on any image enable the
mirroring on the dummy image. when we enable the mirroring
on the dummy image the pool will get updated and the
scheduling will be reconfigured.

* During Demote operation on any image disable the mirroring
on the dummy image. the disable need to be done to enable
the mirroring again when we get the promote request to make
the image as primary

* When the DR is no more needed, this image need to be
manually cleanup as for now as we dont want to add a check
in the existing DeleteVolume code path for delete dummy image
as it impact the performance of the DeleteVolume workflow.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>