monitoring: fix NVMeoFMultipleNamespacesOfRBDImage

Do not trigger alert NVMeoFMultipleNamespacesOfRBDImage
for same pool/image name used in multiple nvmeof namespaces,
if they are in different rados namespaces (rados_namespace_name)

These are valid repeation of pool/image name:
- mypool/rados_ns1/myimage1
- mypool/rados_ns2/myimage1
- mypool/myimage1 (default rados namespace)

Fixes: https://tracker.ceph.com/issues/77128

Signed-off-by: Vallari Agrawal <vallari.agrawal@ibm.com>