Make leader to delete the raft repl dev in UT.

[sanebay]

UT hangs as deletion repl dev causes follower not find to the leader, Keep the leader up till all the followers leave. There is still some issue with nuraft_mesg with client not connecting sometimes. This needs to be debugged separately.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 56.59%. Comparing base (1a0cef8) to head (567491d).
Report is 40 commits behind head on master.

Files	Patch %	Lines
src/lib/replication/repl_dev/raft_repl_dev.cpp	0.00%	3 Missing ⚠️
src/lib/replication/service/raft_repl_service.cpp	0.00%	2 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #500      +/-   ##
==========================================
+ Coverage   56.51%   56.59%   +0.07%     
==========================================
  Files         108      109       +1     
  Lines       10300    10517     +217     
  Branches     1402     1432      +30     
==========================================
+ Hits         5821     5952     +131     
- Misses       3894     3959      +65     
- Partials      585      606      +21     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.