rgw: Disable prefetch of entire head object when GET request with range header

rgw: Disable prefetch of entire head object when GET request with range header

Disable prefetch of entire head object when GET request with range header.
The current behavior for the RGW is getting the whole object although the client asked only for a small bytes offset.
For example: If the client asked for bytes=0-1, The RGW will anyway fetch 0-4194304

Fixes: https://tracker.ceph.com/issues/44508
Signed-off-by: Or Friedmann <ofriedma@redhat.com>
(cherry picked from commit 2be5af0006169cb54547034aa98b7eacb8751d59)