message: move the sst files instead of copying them
diff: #include "kvstore/RocksEngineConfig.h"
  #include "utils/NebulaKeyUtils.h"
  +DEFINE_bool(move_files, false,
  + "Move the SST files instead of copy when ingest into dataset");
  +
  namespace nebula {
  namespace kvstore {
  @@ -336,6 +339,7 @@ int32_t RocksEngine::totalPartsNum() {
  ResultCode RocksEngine::ingest(const std::vector<std::string>& files) {
  rocksdb::IngestExternalFileOptions options;
  + options.move_files = FLAGS_move_files;
  rocksdb::Status status = db_->IngestExternalFile(files, options);
  if (status.ok()) {
  return ResultCode::SUCCEEDED;
  