8239852: java/util/concurrent tests fail with -XX:+VerifyGraphEdges: assert(!VerifyGraphEdges) failed: verification should have failed

Remove an assertion which was too strong for some valid IRs when running with -XX:+VerifyGraphEdges

Reviewed-by: neliasso, thartmann

src/hotspot/share/opto/gcm.cpp

@@ -1439,8 +1439,6 @@ void PhaseCFG::global_code_motion() {
   // ( visited.clear() called in schedule_late()->Node_Backward_Iterator() )
   schedule_late(visited, stack);
   if (C->failing()) {
-    // schedule_late fails only when graph is incorrect.
-    assert(!VerifyGraphEdges, "verification should have failed");
     return;
   }