*: use another etcd client for election (#6409)

[ti-chi-bot]

This is an automated cherry-pick of #6409

What problem does this PR solve?

Issue Number: Ref #6403.

What is changed and how does it work?

This PR tries to use another etcd client for the election to prevent the throttling of one connection.

Check List

Tests

• Manual test (TODO)

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lhy1024
• nolouch

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[lhy1024]

need fix conflict

[nolouch]

cc @rleungx

[codecov]

Codecov Report

Patch coverage: 46.66% and no project coverage change.

Comparison is base (f1b5566) 74.92% compared to head (82398a0) 74.92%.

❗ Current head 82398a0 differs from pull request most recent head 782ace4. Consider uploading reports for the commit 782ace4 to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##           release-7.1    #6455   +/-   ##
============================================
  Coverage        74.92%   74.92%           
============================================
  Files              408      408           
  Lines            40671    40648   -23     
============================================
- Hits             30472    30457   -15     
+ Misses            7527     7525    -2     
+ Partials          2672     2666    -6     

Flag	Coverage Δ
unittests	74.92% <46.66%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
server/server.go	74.44% <42.85%> (-0.84%)	⬇️
pkg/utils/etcdutil/etcdutil.go	81.81% <100.00%> (+1.94%)	⬆️

... and 29 files with indirect coverage changes

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[nolouch]

/merge

[ti-chi-bot]

@nolouch: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 82398a0

[ti-chi-bot]

@ti-chi-bot: Your PR was out of date, I have automatically updated it for you.

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