Error printed to stderr when calling `get_vsi_mem_file_bytes_owned`

Whenever I call `get_vsi_mem_file_bytes_owned` the operation appears to succeed with no error, however the following is always written to stderr:

```
ERROR 6: Cannot extended in-memory file whose ownership was not transferred
```

I worked around this by doing the following, which has the same effect as `get_vsi_mem_file_bytes_owned`, but doesn't produce the error message:

```rust
let mut owned_bytes = vec![];
gdal::vsi::call_on_mem_file_bytes(
"/vsimem/some_path,
|bytes| {
owned_bytes.extend_from_slice(bytes);
},
)?;
```

Start by tracing the implementation of `get_vsi_mem_file_bytes_owned` and compare it with the reported `call_on_mem_file_bytes` workaround. Reproduce the call and verify that the owned-byte result remains correct without writing the ownership error to stderr.

Written by the indexing model from the issue text.