Fix pad token id issue for transformers v5 support

[vaibhavjindal]

Summary

Fix multiple failing monkey_patch tests for transformers v5. The tests failed because of huggingface/transformers#41541.

These changes are backward compatible.

This change fixes the following failing tests:

FAILED test/transformers/test_monkey_patch.py::test_apply_liger_kernel_to_instance_for_qwen3_vl_moe_for_conditional_generation - AttributeError: 'Qwen3VLMoeTextConfig' object has no attribute 'pad_token_id'
FAILED test/transformers/test_monkey_patch.py::test_apply_liger_kernel_to_instance_for_qwen3_vl_moe - AttributeError: 'Qwen3VLMoeTextConfig' object has no attribute 'pad_token_id'
FAILED test/transformers/test_monkey_patch.py::test_apply_liger_kernel_to_instance_for_qwen3_vl_moe_text - AttributeError: 'Qwen3VLMoeTextConfig' object has no attribute 'pad_token_id'
FAILED test/transformers/test_monkey_patch.py::test_apply_liger_kernel_to_instance_for_llama4_for_conditional_generation - AttributeError: 'Llama4Config' object has no attribute 'pad_token_id'
FAILED test/transformers/test_monkey_patch.py::test_apply_liger_kernel_to_instance_for_glm4v - AttributeError: 'Glm4vTextConfig' object has no attribute 'pad_token_id'

Fixes #1059.

Testing Done

• Hardware Type:
• run make test to ensure correctness
• run make checkstyle to ensure code style
• run make test-convergence to ensure convergence

[vaibhavjindal]

@Tcc0403 @shimizust @Mecoli1219 for review

[Tcc0403]

Thanks LGTM

[vaibhavjindal]

#1059