[leofs_test2] Expand the test suites towards v0.6

[mocchira]

With https://github.com/project-fifo/libleofs/pull/1, we are going to implement

• https://github.com/leo-project/leofs_test2#v04-improve-the-basic-scenarios-retrieved-from-leofs-adms-commands
• https://github.com/leo-project/leofs_test2#v06-implement-the-advanced-scenarios-mainly-in-case-of-failures

to increase the integration test coverage.

In addition to the above milestones (0.4, 0.6), we will also implement the below suites

• leo_storage cluster works without leo_manager
  • master
  • slave
  • both
• relatively large leo_storage cluster works with two or more storages being dead
• leo_storage cluster works while recover-disk is ongoing
• leo_storage cluster works while recover-node is ongoing
• leo_storage cluster works while recover-consistency is ongoing
• CDN integration test suites
• Confirm whether the compaction rollback works as expected when the large garbage exists in AVS
• Confirm whether issuing the unsupported S3 API doesn't harm any data stored in leo_storage
• Confirm whether any type of updates are atomic
  • Without https://github.com/leo-project/leofs/issues/719 fixed, we can't pass this test suite though
• recover-file for a large object
  • with children
  • with grand-children