message: remove chain_op from map when kConditional
  Summary: Fix occasional failures. Corrupted instruction in flattened_inst_map_bwd.
  Test Plan: All test OK.
  Reviewers: #tensorflow, davidn, georgep, jakeh, stephenm
  Subscribers: stephenm, jakeh, georgep, davidn, #tensorflow
  Maniphest Tasks: T11920
diff: @@ -132,6 +132,7 @@ StatusOr<bool> ModuleFlatten::Run(HloModule* module) {
  auto* caller = call_site.instruction();
  if (caller->opcode() == HloOpcode::kCall) {
  caller->DropAllControlDeps();
  + RemoveMapEntry(caller);
  TF_ASSIGN_OR_RETURN(CallInliner::InlinedInstructionMap map,
  CallInliner::Inline(caller));
  