etcdutil: return original endpoints when all are evicted

[JmPotato]

What problem does this PR solve?

Issue Number: ref #7730, ref #7499.

What is changed and how does it work?

Return the originally picked endpoints directly if all are evicted to gain better availability.

Check List

Tests

• Unit test
• Integration test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• HuSharp
• rleungx

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[codecov]

Codecov Report

Merging #7779 (4af2f53) into master (1c54865) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7779      +/-   ##
==========================================
- Coverage   73.65%   73.63%   -0.03%     
==========================================
  Files         430      430              
  Lines       47740    47745       +5     
==========================================
- Hits        35164    35157       -7     
- Misses       9578     9586       +8     
- Partials     2998     3002       +4     

Flag	Coverage Δ
unittests	73.63% <100.00%> (-0.03%)	⬇️

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[HuSharp]

Can you provide more information in the log message etcd client is closed, exit update endpoint goroutine to distinguish the situations in syncer and inspector?

[JmPotato]

/merge

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[ti-chi-bot]

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

Commit hash: 4af2f53