CLOUDSTACK-6783: Return a proper LibvirtStoragePool object after creating the pool

In situations where libvirt lost the storage pool the KVM Agent will re-create the
storage pool in libvirt.

This could be then libvirt is restarted for example.

The object returned internally was missing essential information like the sourceDir
aka the Ceph pool, the monitor IPs, cephx information and such.

In this case the first operation on this newly created pool would fail. All operations
afterwards would succeed.