ci: add check for .mgr pool in rook.sh
ci: add check for .mgr pool in rook.sh

Rook v1.9.x creates pool with name .mgr
for builtin-mgr CephBlockPool CR.

Signed-off-by: Madhu Rajanna <60fbf37a92c2a0908e31296d18dadbec5a4dae17@gmail.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi