[CI] Fix mypy for vllm/executor

[yewentao256]

Purpose

Part of the #26533

Test

(vllm-user-6) vllm-user-6@centralia:~/vllm-source$ pre-commit run --hook-stage manual mypy-3.10 -a
Run mypy for Python 3.10.................................................Passed

[gemini-code-assist]

Code Review

This pull request focuses on fixing mypy type checking errors, primarily by moving the vllm/executor module to a group with stricter checks. The changes involve adding more precise type hints, using assert statements for type narrowing, and suppressing unavoidable mypy errors in Ray actor code with # type: ignore. These modifications improve the codebase's type safety and are well-aligned with the goal of resolving CI issues. The changes appear correct and I have no high or critical severity concerns.

[DarkLight1337]

This directory is V0 code which will be removed soon anyways, I think there is not much value in fixing mypy here

[hmellor]

Given that the work has been done and the tests pass, could we merge anyway?

The timeline for removal of all remaining V0 code is uncertain and doing this would allow us to push forward with running mypy directly instead of via our complicated script.

[DarkLight1337]

OK then