feat: implement retry logic for etcd server start using retry util

[amaypatil02]

issue: #47104
issue related: #17569

Related PR: #34208

etcd server start retry with internal retry util package.
github.com/milvus-io/milvus/pkg/util/retry

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[gemini-code-assist]

Summary of Changes

Hello @amaypatil02, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refactors the embedded etcd server's startup and readiness check retry mechanisms to leverage a common internal retry utility. This change introduces more sophisticated retry options, including exponential backoff, to improve the reliability of etcd initialization. Additionally, a minor correction has been applied to Grafana dashboard configurations to ensure accurate monitoring of query node time-tick lag metrics.

Highlights

• Standardized Etcd Retry Logic: The custom retry function for embedded etcd server startup has been replaced with a standardized internal retry utility (github.com/milvus-io/milvus/pkg/util/retry).
• Exponential Backoff for Etcd Retries: The new retry mechanism for etcd startup now incorporates exponential backoff, with a configurable maximum sleep interval (defaultMaxSleepInterval = 2 * time.Second), enhancing robustness during initialization.
• Grafana Dashboard Metric Correction: Grafana dashboard expressions for milvus_querynode_consume_tt_lag_ms metrics (average, maximum, and minimum) have been updated to correctly filter by msg_type="timetick" instead of msg_type="insert".
• Updated Retry Unit Tests: Existing unit tests related to retry functionality in etcd_kv_test.go have been refactored to use the new retry.Do utility and accurately reflect the exponential backoff behavior.

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[mergify]

@amaypatil02 Please associate the related issue to the body of your Pull Request. (eg. "issue: #")

[gemini-code-assist]

Code Review

This pull request refactors the embedded etcd startup logic to use a centralized retry utility, which is a good improvement for code consistency and maintainability. The changes in embed_etcd_kv.go are clean and correctly replace the local retry implementation. The update to the Grafana dashboard in milvus-dashboard.json also appears to be a correct fix for a query metric. My main feedback is on the test file etcd_kv_test.go, where several tests have become redundant after the refactoring. I've suggested removing them to improve test organization.

[mergify]

@amaypatil02 go-sdk check failed, comment rerun go-sdk can trigger the job again.

[mergify]

@amaypatil02 go-sdk check failed, comment rerun go-sdk can trigger the job again.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.95%. Comparing base (9373518) to head (3f54a2a).
⚠️ Report is 11 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #47105       +/-   ##
===========================================
+ Coverage   76.46%   82.95%    +6.48%     
===========================================
  Files        2016      586     -1430     
  Lines      325600    94456   -231144     
===========================================
- Hits       248972    78356   -170616     
+ Misses      68670    16100    -52570     
+ Partials     7958        0     -7958     

Components	Coverage Δ
Client	∅ <ø> (∅)
Core	82.95% <99.47%> (+0.05%)	⬆️
Go	∅ <ø> (∅)
see 1433 files with indirect coverage changes

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