fix. raft follower will rollback itself when it misses a certain log

[UndefinedSy]

What type of PR is this?

• bug
• feature
• enhancement

What problem(s) does this PR solve?

Issue(s) number:

Description:

if a leader fails to update its last_log_id_sent (maybe caused be
follower fail or network issue), it will then try to send some
duplicated logs in the next appendLog request.

```
                      commitId_: 99
                          |
                          v
local wal: |-------------------|
req.append_entries:        |----------------|
```

in this case, follower will do rollback even if the logs are the same.

How do you solve it?

add a bool variable to track if the log is inconsistent and only do rollback if the log has a conflict.

Special notes for your reviewer, ex. impact of this fix, design document, etc:

with this fix, followers will not do unnecessary rollback in network issues.
raft rollback is not a lightweight operation, especially if we have a large number of parts, which may may lead to cascade problems.

Checklist:

Tests:

• Unit test(positive and negative cases)
• Function test
• Performance test
• N/A

Affects:

• Documentation affected (Please add the label if documentation needs to be modified.)
• Incompatibility (If it breaks the compatibility, please describe it and add the label.）
• If it's needed to cherry-pick (If cherry-pick to some branches is required, please label the destination version(s).)
• Performance impacted: Consumes more CPU/Memory

Release notes:

Please confirm whether to be reflected in release notes and how to describe:

ex. Fixed the bug .....

[CLAassistant]

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