[Bugfix] fix dp parallel + tp > 1 offline inference port conflict

[leo-pony]

What this PR does / why we need it?

fix dp parallel + tp > 1 offline inference port conflict

issue import PR:#429

Does this PR introduce any user-facing change?

How was this patch tested?

• vLLM version: v0.11.2
• vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.2

[github-actions]

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[gemini-code-assist]

Code Review

This pull request addresses a port conflict issue that occurs during offline inference in distributed environments using both data parallelism and tensor parallelism (tp > 1). The change removes a monkey-patch for ParallelConfig.get_next_dp_init_port that was causing this conflict. The removed code attempted to manage data parallel ports by incrementing a counter on the ParallelConfig instance. This approach is not safe across multiple processes, as each process would have its own instance and counter, leading to race conditions and port collisions. By deleting this faulty patch, the code now relies on the default port allocation mechanism from the underlying vLLM framework, which should correctly handle multi-process scenarios. This is a clean and effective fix for the described problem.