cc userver: fix some warnings detected by clang-tidy16

Author: georgthegreat

postgresql/src/storages/postgres/dsn.cpp

@@ -142,7 +142,7 @@ DsnList SplitByHost(const Dsn& dsn) {
     if (!ports.empty()) {
       options << " port=" << ports.front();
     }
-    res.push_back(Dsn{options.str()});
+    res.emplace_back(options.str());
   } else {
     if (ports.size() > 1 && ports.size() != hosts.size()) {
       throw InvalidDSN{DsnMaskPassword(dsn), "Invalid port options count"};
@@ -157,7 +157,7 @@ DsnList SplitByHost(const Dsn& dsn) {
         os << " port=" << ports[host - hosts.begin()];
       }
       os << options.str();
-      res.push_back(Dsn{os.str()});
+      res.emplace_back(os.str());
     }
   }
 

redis/src/storages/redis/impl/sentinel_impl.cpp

@@ -764,6 +764,7 @@ bool SentinelImpl::SetConnectionInfo(
 
       if (changed) {
         std::vector<std::string> conn_strs;
+        conn_strs.reserve(info_iterator.second.size());
         for (const auto& conn_str : info_iterator.second)
           conn_strs.push_back(conn_str.Fulltext());
         LOG_INFO() << "Redis state changed for client=" << client_name_

redis/src/storages/redis/pubsub_redistest.cpp

@@ -92,7 +92,7 @@ std::vector<redis::CommandControl> BuildTestData() {
   std::vector<redis::CommandControl> result;
 
   // One default CC
-  result.emplace_back(redis::CommandControl{});
+  result.emplace_back();
 
   return result;
 }