chore(config): migrate partialFlushMinSpans

[mtoffl01]

What does this PR do?

Migrates tracer to use Config.partialFlushMinSpans

Motivation

https://datadoghq.atlassian.net/browse/APMAPI-1745

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• New code is free of linting errors. You can check this by running ./scripts/lint.sh locally.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.

Unsure? Have a question? Request a review!

[mtoffl01]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat(config): Config Visibility - report telemetry about all config sources #4247
• migrate ciVisibilityEnabled #4293
• chore(config): migrate serviceName #4292
• chore(config): migrate retryInterval #4240
• chore(config): migrate serviceMappings #4281
• chore(config): migrate featureFlags #4280
• chore(config): migrate env #4279
• chore(config): migrate version #4278
• chore(config): migrate hostname #4271
• chore(config): migrate logDirectory #4267
• chore(config): migrate statsComputationEnabled #4265
• chore(config): migrate noDebugStack #4264
• chore(config): migrate spanTimeout #4263
• chore(config): migrate debugAbandonedSpans #4262
• chore(config): migrate dynamicInstrumentationEnabled #4261
• chore(config): migrate partialFlushMinSpans #4260 👈 (View in Graphite)
• chore(config): migrate partialFlushEnabled #4259
• chore(config): migrate first chunk tracer configs #4258
• chore(config): migrate globalSampleRate and introduce configProvider.getFloatWithValidator #4257
• chore(config): migrate logToStdout and isLambdaFunction #4256
• main

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[pr-commenter]

Benchmarks

Benchmark execution time: 2025-12-19 17:24:25

Comparing candidate commit a325530 in PR branch 12-12-migrate_partialflushminspans with baseline commit 4c491d3 in branch 12-12-migrate_partialflushenabled.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 6 metrics, 0 unstable metrics.

[hannahkm]

In the deleted code (ddtrace/tracer/option.go L427-430), minSpans values == 0 or TraceMaxSize were considered invalid. Should we keep that here?

[codecov]

Codecov Report

❌ Patch coverage is 17.24138% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.59%. Comparing base (4c491d3) to head (a325530).

Files with missing lines	Patch %	Lines
internal/config/config.go	10.00%	9 Missing ⚠️
internal/config/config_helpers.go	0.00%	8 Missing ⚠️
internal/config/configprovider.go	12.50%	6 Missing and 1 partial ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
ddtrace/tracer/log.go	86.51% <100.00%> (ø)
ddtrace/tracer/option.go	84.25% <100.00%> (-0.18%)	⬇️
ddtrace/tracer/spancontext.go	90.18% <ø> (ø)
ddtrace/tracer/tracer.go	86.40% <100.00%> (ø)
internal/config/configprovider.go	78.26% <12.50%> (-6.27%)	⬇️
internal/config/config_helpers.go	0.00% <0.00%> (ø)
internal/config/config.go	27.93% <10.00%> (-1.48%)	⬇️

... and 1 file with indirect coverage changes

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[genesor]

Should we validate the values passed via programatic API ?