[Fix]Revert temporary skip on mtp1/mtp2 correctness tests (aclgraph fix)

[MrZ20]

What this PR does / why we need it?

This Pull Request removes the @pytest.mark.skip decorators from test_mtp1_correctness_piecewise_graph and test_mtp2_correctness_piecewise_graph.

These tests were temporarily skipped because of an issue with the MTP ACL Graph (as per the original TODO comment). Since the relevant bug/issue has been resolved, these tests are now re-enabled to ensure full correctness coverage for MTP functionality.

Does this PR introduce any user-facing change?

How was this patch tested?

• vLLM version: v0.12.0
• vLLM main: vllm-project/vllm@ad32e3e

[gemini-code-assist]

Code Review

This pull request re-enables two MTP correctness tests, test_mtp1_correctness_piecewise_graph and test_mtp2_correctness_piecewise_graph, by removing their @pytest.mark.skip decorators. This is a welcome change that restores test coverage, following a fix for an issue with MTP ACL Graph. The changes are correct. While reviewing, I noticed that test_mtp1_correctness_piecewise_graph_with_pad and test_mtp2_correctness_piecewise_graph_with_pad remain skipped with a similar reason. It would be beneficial to verify if the current fix also resolves the issue for these _with_pad variants, and if so, re-enable them as well to ensure comprehensive test coverage for MTP functionality.

[github-actions]

👋 Hi! Thank you for contributing to the vLLM Ascend project. The following points will speed up your PR merge:‌‌

• A PR should do only one thing, smaller PRs enable faster reviews.
• Every PR should include unit tests and end-to-end tests ‌to ensure it works and is not broken by other future PRs.
• Write the commit message by fulfilling the PR description to help reviewer and future developers understand.

If CI fails, you can run linting and testing checks locally according Contributing and Testing.

[MengqingCao]

CI failed due to unrelated cases, let's merge this quickly to unblock CI on mtp + aclgraph
https://github.com/vllm-project/vllm-ascend/actions/runs/20230899827/job/58073980686?pr=5039