rgw: lower some debug message

Fixes: #6084
Backport: dumpling, emperor

Reported-by: Ron Allred <rallred@itrefined.com>
Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
(cherry picked from commit b35fc1bc2ec8c8376ec173eb1c3e538e02c1694e)