message: fix unstable testcase index_scan_test
diff: #include "dataman/RowSetReader.h"
  #include "dataman/RowReader.h"
  +DECLARE_uint32(raft_heartbeat_interval_secs);
  +
  namespace nebula {
  namespace storage {
  using IndexValues = std::vector<std::pair<nebula::cpp2::SupportedType, std::string>>;
  @@ -371,6 +373,7 @@ static cpp2::LookUpEdgeIndexResp checkLookupEdgesString(const std::string& filte
  }
  std::unique_ptr<meta::IndexManager> indexMan(im);
  auto eindex = indexMan->getEdgeIndex(spaceId, type).value();
  + sleep(FLAGS_raft_heartbeat_interval_secs);
  {
  for (auto partId = 0; partId < 3; partId++) {
  std::vector<kvstore::KV> data;
  @@ -462,6 +465,7 @@ static cpp2::LookUpVertexIndexResp checkLookupVerticesString(const std::string&
  }
  std::unique_ptr<meta::IndexManager> indexMan(im);
  auto vindex = indexMan->getTagIndex(spaceId, tagId).value();
  + sleep(FLAGS_raft_heartbeat_interval_secs);
  {
  for (auto partId = 0; partId < 3; partId++) {
  std::vector<kvstore::KV> data;
  @@ -552,6 +556,7 @@ static cpp2::LookUpEdgeIndexResp checkLookupEdgesDouble(const std::string& filte
  }
  std::unique_ptr<meta::IndexManager> indexMan(im);
  auto eindex = indexMan->getEdgeIndex(spaceId, type).value();
  + sleep(FLAGS_raft_heartbeat_interval_secs);
  {
  for (auto partId = 0; partId < 3; partId++) {
  std::vector<kvstore::KV> data;
  @@ -647,6 +652,7 @@ static cpp2::LookUpVertexIndexResp checkLookupVerticesDouble(const std::string&
  }
  std::unique_ptr<meta::IndexManager> indexMan(im);
  auto vindex = indexMan->getTagIndex(spaceId, tagId).value();
  + sleep(FLAGS_raft_heartbeat_interval_secs);
  {
  for (auto partId = 0; partId < 3; partId++) {
  std::vector<kvstore::KV> data;
  