chore(config): migrate tracer.retryInterval

[mtoffl01]

What does this PR do?

Tracer migrates to using Config.logStartup instead of its own config.logStartup.

Motivation

datadoghq.atlassian.net/browse/APMAPI-1748

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!

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-12-10 19:51:36

Comparing candidate commit c8e1968 in PR branch mtoff/retryInterval with baseline commit b760677 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 9 metrics, 0 unstable metrics.

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.38%. Comparing base (0fc0961) to head (c8e1968).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/config/config.go	9.09%	10 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
ddtrace/tracer/civisibility_writer.go	78.00% <100.00%> (ø)
ddtrace/tracer/option.go	85.18% <100.00%> (+0.56%)	⬆️
ddtrace/tracer/telemetry.go	87.50% <100.00%> (ø)
ddtrace/tracer/writer.go	91.70% <100.00%> (ø)
internal/config/config.go	71.42% <9.09%> (-28.58%)	⬇️

... and 76 files with indirect coverage changes

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[mtoffl01]

For changes to this test, see: dd.slack.com/archives/C03D7LNP0TD/p1765313037158839

by newly importing internalconfig "github.com/DataDog/dd-trace-go/v2/internal/config", I believe that triggered a dependency tree that caused processtags init() function to run earlier than it did before. As a result, processtags.enabled evaluated to true (by default), and process tags were appended onto span metadata, causing the payload size to increase from 185 bytes to 308.

[genesor]

As the init() is ran earlier than before, could it trigger some unwanted behavior in other places or in deployed code ?

[genesor]

Same question as in another PR, is this the same env var as other tracer if they have this feature ?

[genesor]

As the init() is ran earlier than before, could it trigger some unwanted behavior in other places or in deployed code ?