[VPlan] Fix unit test without LLVM_ENABLE_DUMP. NFC

Without dumping the faulty recipe isn't printed, so account for that
like in the other tests. Fixes the buildbot failure at
https://lab.llvm.org/buildbot/#/builders/2/builds/30229

Author: lukel97

llvm/unittests/Transforms/Vectorize/VPlanVerifierTest.cpp

@@ -312,9 +312,14 @@ TEST_F(VPVerifierTest, NonHeaderPHIInHeader) {
 #endif
   EXPECT_FALSE(verifyVPlanIsValid(Plan));
 #if GTEST_HAS_STREAM_REDIRECTION
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
   EXPECT_STREQ(
       "Found non-header PHI recipe in header VPBB: IR   <badref> = phi i32 \n",
       ::testing::internal::GetCapturedStderr().c_str());
+#else
+  EXPECT_STREQ("Found non-header PHI recipe in header VPBB",
+               ::testing::internal::GetCapturedStderr().c_str());
+#endif
 #endif
 }