Avoid dup-append logs for committing logs

[Besroy]

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Codecov Report

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 67.42%. Comparing base (1a0cef8) to head (431ac5d). Report is 220 commits behind head on master.

Files with missing lines	Patch %	Lines
src/lib/replication/repl_dev/raft_repl_dev.cpp	57.14%	2 Missing and 1 partial :warning:

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Additional details and impacted files

@@             Coverage Diff             @@
##           master     #757       +/-   ##
===========================================
+ Coverage   56.51%   67.42%   +10.91%     
===========================================
  Files         108      109        +1     
  Lines       10300    12384     +2084     
  Branches     1402     1748      +346     
===========================================
+ Hits         5821     8350     +2529     
+ Misses       3894     3139      -755     
- Partials      585      895      +310     

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[Besroy]

This pr aims to resole a corner case, but using last_lsn/last_term rather than last_commit_lsn might be more dangerous and requires more consideration, so covert it to raft ATM.