test: added new checksums for flaky tests

  box/net.box_incorrect_iterator_gh-841.test.lua	gh-5434
  replication/election_basic.test.lua			gh-5368
  replication/election_qsync.test.lua			gh-5430
  replication/election_qsync_stress.test.lua		gh-5395
  replication/gh-4402-info-errno.test.lua		gh-5366
  replication/gh-5426-election-on-off.test.lua		gh-5433
  wal_off/snapshot_stress.test.lua			gh-5431