Still have incorrect skip flush change set because of commitTS inconsistency. about unistore HOT 4 CLOSED

CommitTS is used as the version of Lock CF and also used to order the L0 files.

In order to complete solve the inconsistency problem, we should remove the commitTS and use the raft log index instead.

from unistore.

The newly split region's initial raft log index should inherent the parent region's raft log index, so the old L0 table's sequence will always be smaller than new L0 table's sequence.

from unistore.

Changing the initial index of a raft group may cause some potential problems. In kv engine, adding parent index to shard may be a better choice. Using the new split region's index plus parent index as the commit timestamp. The commit timestamp will keep increments sequentially from the old region to the new region.

from unistore.

Fixed by #632

from unistore.