fix: remove parentIsObject() check (#12851)

we will allow situations such as

```
a/b/1.txt
a/b
```

and

```
a/b
a/b/1.txt
```

we are going to document that this usecase is
not supported and we will never support it, if
any application does this users have to delete
the top level parent to make sure namespace is
accessible at lower level.

rest of the situations where the prefixes get
created across sets are supported as is.

cmd/erasure-sets.go

@@ -878,18 +878,10 @@ func (s *erasureSets) GetObjectNInfo(ctx context.Context, bucket, object string,
 	return set.GetObjectNInfo(ctx, bucket, object, rs, h, lockType, opts)
 }
 
-func (s *erasureSets) parentDirIsObject(ctx context.Context, bucket, parent string) bool {
-	if parent == "." {
-		return false
-	}
-	return s.getHashedSet(parent).parentDirIsObject(ctx, bucket, parent)
-}
-
 // PutObject - writes an object to hashedSet based on the object name.
 func (s *erasureSets) PutObject(ctx context.Context, bucket string, object string, data *PutObjReader, opts ObjectOptions) (objInfo ObjectInfo, err error) {
 	set := s.getHashedSet(object)
 	auditObjectErasureSet(ctx, object, set)
-	opts.ParentIsObject = s.parentDirIsObject
 	return set.PutObject(ctx, bucket, object, data, opts)
 }
 
@@ -1074,7 +1066,6 @@ func (s *erasureSets) AbortMultipartUpload(ctx context.Context, bucket, object,
 func (s *erasureSets) CompleteMultipartUpload(ctx context.Context, bucket, object, uploadID string, uploadedParts []CompletePart, opts ObjectOptions) (objInfo ObjectInfo, err error) {
 	set := s.getHashedSet(object)
 	auditObjectErasureSet(ctx, object, set)
-	opts.ParentIsObject = s.parentDirIsObject
 	return set.CompleteMultipartUpload(ctx, bucket, object, uploadID, uploadedParts, opts)
 }