[#1905] shard: Decrease severity level of write-cache failure logs

In previous implementation `Shard.Delete` logged writecache's removal
failures in `error` level. There is a need to decrease severity of these
log records since they aren't critical and don't require individual
review.

Change level of the message to `info`.

Signed-off-by: Leonard Lyubich <ctulhurider@gmail.com>

pkg/local_object_storage/shard/delete.go

@@ -40,7 +40,7 @@ func (s *Shard) Delete(prm DeletePrm) (DeleteRes, error) {
 		if s.hasWriteCache() {
 			err := s.writeCache.Delete(prm.addr[i])
 			if err != nil && !IsErrNotFound(err) {
-				s.log.Error("can't delete object from write cache", zap.String("error", err.Error()))
+				s.log.Warn("can't delete object from write cache", zap.String("error", err.Error()))
 			}
 		}