improve node_hint metrics

[qrort]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

node_hint_miss metric reports node_hint info for all requests, even when preferred session_id equals actual session_id

What is the new behavior?

added "hit" label to metrics to distinguish between hits and misses

Other information

[github-actions]

summary

Inferred base version: v3.124.0
Suggested version: v3.124.1

[codecov-commenter]

Codecov Report

❌ Patch coverage is 11.11111% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.08%. Comparing base (d9d08f6) to head (aad52f6).

Files with missing lines	Patch %	Lines
metrics/query.go	14.28%	6 Missing ⚠️
metrics/table.go	14.28%	6 Missing ⚠️
metrics/node_id.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1990      +/-   ##
==========================================
+ Coverage   73.73%   74.08%   +0.35%     
==========================================
  Files         396      396              
  Lines       41251    34645    -6606     
==========================================
- Hits        30415    25667    -4748     
+ Misses       9721     7852    -1869     
- Partials     1115     1126      +11     

Flag	Coverage Δ
experiment	73.74% <11.11%> (+0.35%)	⬆️
go-1.21.x	72.93% <11.11%> (+3.86%)	⬆️
go-1.25.x	74.06% <11.11%> (+0.37%)	⬆️
integration	55.07% <11.11%> (+0.87%)	⬆️
macOS	47.70% <0.00%> (-0.07%)	⬇️
ubuntu	74.08% <11.11%> (+0.37%)	⬆️
unit	47.71% <0.00%> (-0.06%)	⬇️
windows	47.69% <0.00%> (-0.04%)	⬇️
ydb-24.4	54.26% <11.11%> (+0.89%)	⬆️
ydb-25.2	55.01% <11.11%> (+1.11%)	⬆️
ydb-latest	54.59% <11.11%> (+1.06%)	⬆️
ydb-nightly	73.74% <11.11%> (+0.35%)	⬆️

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[github-actions]

🌋 SLO Test Results

Status: 🟡 6 workloads tested • 6 workloads with warnings

	Workload	Metrics	Regressions	Improvements	Links
🟡	native-table	8	0	0	Report • Check
🟡	native-bulk-upsert	8	0	0	Report • Check
🟡	native-query	8	0	0	Report • Check
🟡	native-table-over-query-service	8	0	1	Report • Check
🟡	database-sql-query	8	0	0	Report • Check
🟡	database-sql-table	8	0	0	Report • Check

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Generated by ydb-slo-action

[Copilot]

Pull request overview

This PR improves the node_hint metrics by renaming the metrics from node_hint_miss to node_hint and adding a "hit" label to distinguish between cache hits and misses, addressing the issue where the previous implementation reported all requests as misses even when the preferred session ID matched the actual session ID.

• Renamed metrics from *_node_hint_miss to *_node_hint with an added "hit" label
• Introduced string constants trueStr and falseStr for consistent labeling
• Implemented hit/miss detection logic based on comparison of preferred and actual node IDs

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
metrics/query.go	Added constants and updated node hint metric with hit detection logic for query pool
metrics/table.go	Updated node hint metric with hit detection logic for table pool, using constants from query.go
CHANGELOG.md	Documented the breaking change in metric naming and added hit label feature

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[Copilot]

@asmyasnikov I've opened a new pull request, #1991, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@asmyasnikov I've opened a new pull request, #1992, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@asmyasnikov I've opened a new pull request, #1993, to work on those changes. Once the pull request is ready, I'll request review from you.