Add challenge to the elastic/log track which upgrades a data stream

[parkertimmins]

Add a new challenge which test the performance of upgrading a data stream using the reindex data stream endpoints.

This challenge does the following:

• restores a data stream from a snapshot
• starts a data stream upgrade with a call to /_migration/reindex
• waits for the upgrade to complete, polling /_migration/reindex/<data-stream>/_status once a second

The following upgrade specific parameters can be set. These describe the settings described here.

• reindex_max_concurrent_indices
• reindex_max_requests_per_second

The only data stream indices which (currently) require upgrades are 7.x indices in version 8 ES, in preparation for an upgrade to 9.x. To obtain a data stream with 7.x indices we load the data stream from a snapshot. This challenge reuses the existing snapshot parameters used by the logging-snapshot-restore challenge.
The following snapshot parameters should be set:

  "restore_data_streams"
  "snapshot_repo_name"
  "snapshot_repo_type"
  "snapshot_repo_settings"
  "snapshot_name"
  "snapshot_rename_suffix"

[inqueue]

LGTM, nice work