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GH-34988: [C#] Fix Windows-specific test issue in CDataSchemaPythonTest (#34989)

### Rationale for this change

Fixes issue described in referenced bug.

### What changes are included in this PR?

Changes test initialization under Windows to add a references to the "DLLs" subdirectory containing _socket.pyd.

### Are these changes tested?

Covered by existing tests.

### Are there any user-facing changes?

No.
* Closes: #34988

Authored-by: Curt Hagenlocher <curt@hagenlocher.org>
Signed-off-by: Eric Erhardt <eric.erhardt@microsoft.com>