ci: add etcd schema verification for secondary restore

[huanghaoyuanhhy]

Summary

• Add standalone tool cmd/etcd-schema-verify that reads collection metadata directly from etcd and compares source vs target schemas at the etcd level
• Covers fields invisible to DescribeCollection: internal field IDs, field states, index params, partition states, function schemas
• CDC scenario aware: compares all IDs (collection/field/partition/index) since they are preserved across clusters
• Integrate into secondary restore CI to verify schema alignment after restore

Changes

• cmd/etcd-schema-verify/ — standalone Go binary with flag-based CLI
  • Reads databases, collections, fields, partitions, indexes, functions from etcd via protobuf deserialization
  • Diff logic matches by ID, outputs JSON with aligned flag and detailed diffs
  • Exit code 1 when not aligned (CI friendly)
• .github/workflows/main.yaml — build the tool and run it after secondary restore for hello_milvus and hello_milvus2

/kind improvement

[codecov-commenter]

Codecov Report

❌ Patch coverage is 78.04348% with 101 lines in your changes missing coverage. Please review.
✅ Project coverage is 27.93%. Comparing base (1f41db4) to head (672a87d).

Files with missing lines	Patch %	Lines
cmd/etcd-schema-verify/main.go	0.00%	59 Missing ⚠️
cmd/etcd-schema-verify/dump.go	80.46%	20 Missing and 22 partials ⚠️

❌ Your patch status has failed because the patch coverage (78.04%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.
❌ Your project status has failed because the head coverage (27.93%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1011      +/-   ##
==========================================
+ Coverage   25.44%   27.93%   +2.48%     
==========================================
  Files         100      103       +3     
  Lines        9270     9730     +460     
==========================================
+ Hits         2359     2718     +359     
- Misses       6734     6813      +79     
- Partials      177      199      +22     

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[wenhuiZilliz]

/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: huanghaoyuanhhy, wenhuiZilliz

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