message: De-flake and re-enable asan c_api test.
  Treat replaced workers as removed then added back, so that there is one and only one copy of remote task name in the remote_contexts_ list.
diff: @@ -465,9 +465,19 @@ tensorflow::Status UpdateTFE_ContextWithServerDef(
  LOG_AND_RETURN_IF_ERROR(GetReplacedFromExistingWorkers(
  &existing_workers, context_id, ctx->context->GetContextViewId(),
  server_def, remote_eager_workers.get(), &replaced_workers));
  + if (VLOG_IS_ON(1)) {
  + VLOG(1) << "Updating cluster with following changes";
  + for (const string& w : added_workers) VLOG(1) << " Added worker " << w;
  + for (const string& w : removed_workers)
  + VLOG(1) << " Removed worker " << w;
  + for (const string& w : replaced_workers)
  + VLOG(1) << " Replaced worker " << w;
  + }
  if (!replaced_workers.empty()) {
  - // Also adding replaced workers so that we recreate remote devices and
  - // contexts, and re-register functions on those workers
  + // Treat replaced workers as removed then added back, so that we recreate
  + // remote devices and contexts, and re-register functions on those workers
  + removed_workers.insert(removed_workers.end(), replaced_workers.begin(),
  + replaced_workers.end());
  added_workers.insert(added_workers.end(), replaced_workers.begin(),
  replaced_workers.end());
  for (const string& w : replaced_workers) {
  @@ -476,18 +486,8 @@ tensorflow::Status UpdateTFE_ContextWithServerDef(
  existing_workers.end());
  }
  }
  - if (VLOG_IS_ON(1)) {
  - VLOG(1) << "Updating cluster with following changes";
  - for (const string& w : added_workers) VLOG(1) << " Added worker " << w;
  - for (const string& w : removed_workers)
  - VLOG(1) << " Removed worker " << w;
  - for (const string& w : replaced_workers)
  - VLOG(1) << " Replaced worker " << w;
  - }
  LOG_AND_RETURN_IF_ERROR(
  RemoveRemoteDevicesFromMgr(removed_workers, remote_device_mgr.get()));
  - LOG_AND_RETURN_IF_ERROR(
  - RemoveRemoteDevicesFromMgr(replaced_workers, remote_device_mgr.get()));
  LOG_AND_RETURN_IF_ERROR(AddRemoteDevicesToMgr(
  added_workers, grpc_server->master_env()->worker_cache,
  remote_device_mgr.get()));
  