neorados: Fix Neorados CephContext leak and prevent future ones

neorados: Fix Neorados CephContext leak and prevent future ones

The original fix just dropped the extraneous reference. Decided it was
better to make explicitly when a reference was being taken, so
`make_with_cct` no longer accepts `CephContext*` and instead requires
`boost::intrusive_ptr<CephContext>`.

Signed-off-by: Adam C. Emerson <aemerson@redhat.com>
(cherry picked from commit 949e80d0a6e522322d0e00a65feb93f5e13c4655)
Resolves: rhbz#2412500
Signed-off-by: Adam C. Emerson <aemerson@redhat.com>