[CI] Add GLM Image Transformer Model Tests

[DN6]

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Fixes # (issue)

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[yiyixuxu]

looks good to me,
but it's currently failing though

[dg845]

Can you check the output shape here? It looks like the model output shape is the same as the input shape (4, 8, 8), so setting output_shape to (16, 8, 8) causes training tests such as TestGlmImageTransformerTraining.test_training to fail with a shape error.

[dg845]

Thanks for the PR! Left one question about the test output shape.

In addition to the tests which failed in the latest CI run (https://github.com/huggingface/diffusers/actions/runs/23590953774/job/68695918619?pr=13344), I also got the following test failures locally:

1. TestGlmImageTransformerCompile.test_torch_compile_repeated_blocks: I think this can be fixed by setting _repeated_blocks = ["GlmImageTransformerBlock"] in GlmImageTransformer2DModel.
2. TestGlmImageTransformer.test_model_parallelism: it looks like some submodules in GlmImageCombinedTimestepSizeEmbeddings might end up on different devices, causing a device mismatch error. Could you look into it?