enhance: Add WithBlock option for etcd client creation

[congqixia]

Related to #32598

Use WithBlock may fail fast when create etcd client to some invalid etcd endpoints and make it easier to check problem.

[sre-ci-robot]

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[codecov]

Codecov Report

Attention: Patch coverage is 42.85714% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 81.75%. Comparing base (ccce1e9) to head (f54f57d).
Report is 13 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #32641      +/-   ##
==========================================
- Coverage   81.82%   81.75%   -0.07%     
==========================================
  Files         990      998       +8     
  Lines      124483   124042     -441     
==========================================
- Hits       101852   101413     -439     
- Misses      18767    18769       +2     
+ Partials     3864     3860       -4     

Files	Coverage Δ
pkg/util/etcd/etcd_util.go	75.00% <42.85%> (-1.70%)	⬇️

... and 212 files with indirect coverage changes

[weiliu1031]

/lgtm