Fix JIT preload test after Imports Monitor change

Summary:
Stderr is now logging Scuba links for Imports Monitor, this can't assert on the
entire contents of stderr.

Reviewed By: yoney

Differential Revision: D83873217

fbshipit-source-id: c340b3b7c4bd831eab0955785c9e65e793057dae

Author: alexmalyshev

cinderx/PythonLib/test_cinderx/test_jit_preload.py

@@ -125,8 +125,8 @@ def test_error_preloading_inlined(self) -> None:
                 )
                 # We expect an exception, but not a crash!
                 self.assertEqual(proc.returncode, 1, proc.stderr)
-                self.assertEqual(
-                    proc.stderr.decode().splitlines()[-1],
+                self.assertIn(
                     "RuntimeError: boom",
+                    proc.stderr.decode(),
                     proc.stderr,
                 )