crimson/os/seastore/onode_manager: treat ghobjects with different

generations as belonging to the same RADOS object

Different generations of the same RADOS object are treated as different
objects right now. So when EC crimson OSDs do clone_range between them,
the resulted clone operation would violate the invariant that objects
belonging to the same RADOS object should share the same object prefix,
which further leads to the invalid intermediate_keys.

Fixes: https://tracker.ceph.com/issues/78663
Signed-off-by: Xuehan Xu <xuxuehan@qianxin.com>