internal: implement new tag for trace source

[genesor]

What does this PR do?

This PR implements the new RFC that adds support for new tag _dd.p.ts containing the "source" of a trace. This source represents the product that interacted with a trace.

This tag is forwarded to downstream services that will decide wether to keep a trace or not based on their configuration plus the value of this tag.

The representation of this source is 2 character hexadecimal string of the bitmask. (eg: 02 when ASM interacts with a trace)

The RFC also includes the renaming of the env var DD_EXPERIMENTAL_APPSEC_STANDALONE_ENABLED used to disable APM while keeping other product that use traces as their transport active.

✅ System test successful run

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.

[datadog-datadog-prod-us1]

Datadog Report

Branch report: ben.db/APPSEC-56328-asm-standalone-billing-v2
Commit report: 213039e
Test service: dd-trace-go

✅ 0 Failed, 5386 Passed, 72 Skipped, 2m 58.72s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-02-28 13:46:47

Comparing candidate commit 176883a in PR branch ben.db/APPSEC-56328-asm-standalone-billing-v2 with baseline commit e378af5 in branch main.

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

[RamyElkest]

fyi DataDog/system-tests#4216

[kakkoyun]

LGTM

[genesor]

/merge

[dd-devflow]

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2025-02-28 17:20:09 UTC ⚠️ MergeQueue: This merge request was unqueued

devflow unqueued this merge request: It did not become mergeable within the expected time

[genesor]

/merge

[dd-devflow]

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2025-02-28 17:22:27 UTC ℹ️ Start processing command /merge

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2025-02-28 17:22:34 UTC ℹ️ MergeQueue: waiting for PR to be ready

This merge request is not mergeable yet, because of pending checks/missing approvals. It will be added to the queue as soon as checks pass and/or get approvals.
Note: if you pushed new commits since the last approval, you may need additional approval.
You can remove it from the waiting list with /remove command.

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2025-02-28 17:27:17 UTC ℹ️ MergeQueue: This merge request was already merged

This pull request was merged directly.