[XPU]remove is_xxx from moe class

[mayuyuace]

Align with vllm-project/vllm-xpu-kernels#376
Tested below model, results is meaningful.
model=Qwen/Qwen3-30B-A3B
model=openai/gpt-oss-20b
model=Qwen/Qwen3-30B-A3B-FP8
model=INCModel/Qwen3-30B-A3B-Instruct-2507-MXFP8-LLMC
model=INCModel/Qwen3-30B-A3B-MXFP8-LLMC

[mergify]

Hi @mayuyuace, the pre-commit checks have failed. Please run:

uv pip install pre-commit>=4.5.1
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

Tip

Is mypy failing?

mypy is run differently in CI. If the failure is related to this check, please use the following command to run it locally:

# For mypy (substitute "3.10" with the failing version if needed)
pre-commit run --hook-stage manual mypy-3.10

[mayuyuace]

@jikunshang

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @mayuyuace.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[mayuyuace]

New PR for this:
#47256