push_back(std::nullopt) and remove unnecessary lint disablers (#5329)

https://abseil.io/tips/112

Author: wujingyue

csrc/alias_analysis.cpp

@@ -287,7 +287,7 @@ void AliasFinder::handle(const BroadcastOp* bcast) {
   for (const auto i : arange(out_logical.size())) {
     if (bcast->isBroadcastDim(i)) {
       out_allocation.push_back(out_logical[i]);
-      out_contiguity.emplace_back(std::nullopt);
+      out_contiguity.push_back(std::nullopt);
     }
   }
 

csrc/ir/nodes.cpp

@@ -3966,7 +3966,7 @@ std::vector<IterDomain*> TensorDomain::noDevices(
   contiguity.reserve(allocation_domain.size());
   for (auto id : allocation_domain) {
     if (id->isBroadcast() || id->isReduction()) {
-      contiguity.emplace_back(std::nullopt);
+      contiguity.push_back(std::nullopt);
     } else {
       contiguity.emplace_back(fill_value);
     }

csrc/transform_replay.cpp

@@ -339,7 +339,6 @@ void TransformReplay::selfReplay(
       for (auto* id : new_self->logical()) {
         if (id->isReduction()) {
           new_allocation.push_back(id);
-          // NOLINTNEXTLINE(modernize-use-emplace)
           new_contiguities.push_back(std::nullopt);
         }
       }