Fix another test with unstable error order in parallel mode (python#21278)

See
https://github.com/python/mypy/actions/runs/24673382871/job/72150299471

Author: ilevkivskyi

test-data/unit/check-modules.test

@@ -2901,11 +2901,8 @@ from stub import c  # E: Module "stub" has no attribute "c"
 from stub import d  # E: Module "stub" does not explicitly export attribute "d"
 
 [file stub.pyi]
-from mystery import a, b as b, c as d
-
-[out]
-tmp/stub.pyi:1: error: Cannot find implementation or library stub for module named "mystery"
-tmp/stub.pyi:1: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
+from mystery import a, b as b, c as d  # E: Cannot find implementation or library stub for module named "mystery" \
+                                       # N: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
 
 [case testPackagePath]
 import p