rgw: orphan: introduce a detailed mode (off by default)

rgw: orphan: introduce a detailed mode (off by default)

We currently stat objects that fit in a head as well and also log them, since we
skip head objects anyway in the rados list output this commit avoids logging
these objects if the object size itself is less than the manifest head size.

Additionally we avoid the stat call itself from the list object output when the
object fits within the chunk size. This behaviour can be unset by setting the
detailed mode which can help in older clusters where the head used to have a
different size.

The old behaviour in both the cases can be turned on by setting the detailed
flag which can be passed on from rgw-admin. Avoiding stat calls and not logging
the head objects significantly reduces the IO activity on clusters which have a
huge percentage of objects that fit in a head.

Signed-off-by: Abhishek Lekshmanan <abhishek@suse.com>
(cherry picked from commit ca12ecbfed0f65f206e8ad05125fac93c5a5ed0f)