osdc/Objecter: fix ref counts in *Map_Latest

These contexts were putting before continuing to
use the CommandOp/LingerOp.  I added an assert to
reflect that, which was hitting (#9207).

This change is to remove the assertion and put the
put() in the right place (and the end of the function).

Fixes: #9207

Signed-off-by: John Spray <john.spray@redhat.com>