rgw/multisite: remove source object's RGW_ATTR_OBJ_REPLICATION_TRACE during copy_object.

rgw/multisite: remove source object's RGW_ATTR_OBJ_REPLICATION_TRACE during copy_object.
if a copy_object is executed on a replicated object, it fails to sync the copied object
to the original source zone where the source object was first written and replicated from.
this is because copy_object retains source attrs by default. when a get_obj() is issued
from a fetch_remote_obj() call during sync, we check for this RGW_ATTR_OBJ_REPLICATION_TRACE
and if that destination zone is already present in the trace, we return NOT_MODIFIED error,
thus failing to replicate the copied object.

also remove RGW_ATTR_OBJ_REPLICATION_STATUS and RGW_ATTR_OBJ_REPLICATION_TIMESTAMP

Signed-off-by: Shilpa Jagannath <smanjara@redhat.com>