[CI][UT] Fix NetLoader fallback mock binding (vllm-project#11604)

### What this PR does / why we need it?
This PR fixes the NetLoader failure-path UT by patching
`ModelNetLoaderElastic.revert_to_default` on the class instead of
patching a module-level symbol. The production code calls
`self.revert_to_default(...)`, so patching the method keeps the mocked
fallback bound correctly during the test.

### Does this PR introduce _any_ user-facing change?
No. This is a unit test fix only.

### How was this patch tested?
- Stubbed local pytest for this mocked CPU UT passed: `12 passed`.
- `bash format.sh ci` passed ruff, ruff format, codespell, typos,
clang-format, markdownlint, workflow lint, PNG export lint, filename
spacing, package init, forbidden logger/import checks, boolean-op check,
long-function-comment check, and suggestion check. The shellcheck hook
reported an existing issue in unmodified `csrc/build.sh:524`, unrelated
to this PR.
- vLLM version: v0.23.0
- vLLM main:
vllm-project/vllm@1f486d9

Signed-off-by: freyfwt <freytian1996@gmail.com>

Author: freyfwt

tests/ut/model_loader/netloader/test_netloader.py

@@ -281,8 +281,9 @@ def test_failed_target_model_participates_in_barrier_before_error(mock_logger, m
     _patch_loader_common(monkeypatch)
     monkeypatch.setattr("vllm_ascend.model_loader.netloader.netloader.elastic_load", lambda **kwargs: None)
     monkeypatch.setattr(
-        "vllm_ascend.model_loader.netloader.netloader.revert_to_default",
-        lambda *args, **kwargs: (None, False),
+        ModelNetLoaderElastic,
+        "revert_to_default",
+        lambda self, *args, **kwargs: (None, False),
     )
 
     barrier_calls = []