[Bugfix] Fix Qwen3-VL-MoE weight loading for EP

[ywang96]

Purpose

Previously self.load_fused_expert_weights check is too strict and will prevent server from launching with --enable-expert-parallel. This PR fixes it.

Test Plan

The MMMU from server launched with/without --enable-expert-parallel matched.

Test Result

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
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[gemini-code-assist]

Code Review

This pull request fixes a bug in the weight loading logic for Qwen3-VL-MoE models when using expert parallelism (EP). The previous implementation of load_fused_expert_weights was too strict, causing weight loading to fail if any expert was not present on a given rank. The change correctly modifies the logic to consider the loading successful if at least one expert's weights are loaded on the rank, which is the expected behavior for expert parallelism. The changes are correct and effectively address the issue. There is also a minor whitespace change to add a newline at the end of a file.