Remove outdated comment (#6379)

Summary:
Since the logic for handling IDENTITY file is now inside `NewDB`, the comment above `NewDB` is no longer relevant.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6379

Test Plan: not needed

Differential Revision: D19795440

Pulled By: cheng-chang

fbshipit-source-id: 0b1cca87ac6d92474701c46aa4c8d4d708bfa19b

db/db_impl/db_impl_open.cc

@@ -374,9 +374,6 @@ Status DBImpl::Recover(
     s = env_->FileExists(current_fname);
     if (s.IsNotFound()) {
       if (immutable_db_options_.create_if_missing) {
-        // Has to be called only after Identity File creation is successful
-        // because DB ID is stored in Manifest if
-        // immutable_db_options_.write_dbid_to_manifest = true
         s = NewDB();
         is_new_db = true;
         if (!s.ok()) {