[EXPERIMENT] testing/synctest package experiment

[genesor]

⚠️ DO NOT MERGE ⚠️

What does this PR do?

This is an experimentation of the new testing/synctest package

Before:

go test -timeout 45s -run ^TestSendRequestWithTimeout$ github.com/DataDog/dd-trace-go/v2/internal/civisibility/utils/net -v --count=1

=== RUN   TestSendRequestWithTimeout
--- PASS: TestSendRequestWithTimeout (11.71s)
PASS
ok  	github.com/DataDog/dd-trace-go/v2/internal/civisibility/utils/net	12.072s

After:

go test -timeout 45s -run ^TestSendRequestWithTimeout$ github.com/DataDog/dd-trace-go/v2/internal/civisibility/utils/net -tags=goexperiment.synctest -v --count=1

=== RUN   TestSendRequestWithTimeout
--- PASS: TestSendRequestWithTimeout (0.00s)
PASS
ok  	github.com/DataDog/dd-trace-go/v2/internal/civisibility/utils/net	0.336s

Motivation

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.
• 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.
• For internal contributors, a matching PR should be created to the v2-dev branch and reviewed by @DataDog/apm-go.

Unsure? Have a question? Request a review!

[datadog-datadog-prod-us1]

Datadog Report

Branch report: ben.db/sync-test-rd
Commit report: 30e6de7
Test service: dd-trace-go

✅ 0 Failed, 5332 Passed, 72 Skipped, 2m 49.3s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-03-14 15:53:09

Comparing candidate commit 7a1fe4e in PR branch ben.db/sync-test-rd with baseline commit e459938 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 60 metrics, 2 unstable metrics.

[darccio]

Superseded by #3907