[XPU] Fix compile_size is None case.

[jikunshang]

Purpose

previously, we will set compile_sizein init_with_cudagraph_size.
in #25161, xpu platform make support_static_graph_mode is False, which will not fall into previous path and leave compile size be None instead of a empty list even we don't set this.
this PR will set this in xpu.py to avoid runtime error.

Test Plan

CI

Test Result

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[gemini-code-assist]

Code Review

This pull request aims to fix a runtime error on the XPU platform caused by an uninitialized compile_sizes configuration. While the proposed change correctly handles the case where compile_sizes is None, it is incomplete and fails to address scenarios where compile_sizes is configured with the special string "cudagraph_capture_sizes". My review includes a critical comment with a more robust solution that calls the proper initialization method, ensuring that compile_sizes is handled correctly in all cases for platforms that do not support static graphs.

[gemini-code-assist]

This change correctly handles the case where compile_sizes is None. However, it is incomplete and can lead to a runtime error in other scenarios.

Specifically, if a user configures compile_sizes with the special value "cudagraph_capture_sizes", this if condition will not be met, and the special string will not be expanded. This will cause a TypeError later when the code attempts to iterate over it expecting integers.

A more robust solution is to call compilation_config.init_with_cudagraph_sizes(). This method is designed to correctly process the compile_sizes attribute from user configuration. Since XPU does not support CUDA graphs, we can pass an empty list for cudagraph_capture_sizes.

        # `init_with_cudagraph_sizes` is not called on platforms without static
        # graph support. We call it here to ensure `compile_sizes` is
        # correctly initialized from user config.
        compilation_config.init_with_cudagraph_sizes(cudagraph_capture_sizes=[])