[Test] Set DP size in the mocked Metal profiler test

[ch-wan]

Motivation

TestSchedulerProfilerManagerMPS.test_start_profile_success_with_mock_capture fails in _stop_profile() with ValueError: config namespace 'parallel' not published. #40339 changed the DP-width read from self.ps.dp_size to get_parallel().dp_size, but this model-free test only overrides TP rank, PP size, and MoE EP size and never publishes a runtime configuration.

The MLX CI failure on #40638 also reproduces on unmodified main at 15eba3b4643c126ab83e59af3c808b6811075817; the test and failing production path are identical there.

Modifications

Add dp_size=1 to the existing scoped parallel override in the mocked capture test. This is a one-line test-fixture fix; production code is unchanged.

Accuracy Tests

Native Apple Silicon, Python 3.11.16, PyTorch 2.13.0, MLX 0.32.2, with SGLANG_USE_MLX=1 and HF_HUB_OFFLINE=1:

• Before: test_metal_profiler.py runs 10 tests and fails with the same unpublished-parallel error.
• After: all 10 tests pass.
• Pre-commit checks, including registered-test validation, pass.

Speed Tests and Profiling

Not applicable; test-only change.

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CI States

Latest PR Test (Base): 🚫 Run #35680398058
Latest PR Test (Extra): ❌ Run #35680397770
Latest PR Test (AMD ROCm 10): 🚫 Run #35680397847

[ch-wan]

/tag-and-rerun-ci