pools: GetObjectNInfo should cover locking during object read (#14887)
pools: GetObjectNInfo should cover locking during object read (#14887)

In case of multi-pools setup, GetObjectNInfo returns a GetObjectReader
but it unlocks the read lock when quitting GetObjectNInfo. This should
not happen, unlock should only happen when GetObjectReader is closed.
minio/minio,balamurugana/minio,krisis/minio,minio/minio,donatello/minio,vadmeste/minio,donatello/minio,vadmeste/minio,balamurugana/minio,krisis/minio