secondary instance: remove unnessisary cfds_changed->count() (#13086)

Summary:
`cfds_changed->count(cfd)` is not needed, just blind insert.

Pull Request resolved: facebook/rocksdb#13086

Reviewed By: hx235

Differential Revision: D64712400

Pulled By: cbi42

fbshipit-source-id: 4ef62aaa724c8397baa4ff350c16a7a8d04d7067

db/db_impl/db_impl_secondary.cc

@@ -247,9 +247,7 @@ Status DBImplSecondary::RecoverLogFiles(
           if (cfd == nullptr) {
             continue;
           }
-          if (cfds_changed->count(cfd) == 0) {
-            cfds_changed->insert(cfd);
-          }
+          cfds_changed->insert(cfd);
           const std::vector<FileMetaData*>& l0_files =
               cfd->current()->storage_info()->LevelFiles(0);
           SequenceNumber seq =