chore(asm): standalone asm propagation

[gnufede]

Description:

ASM: adds Standalone ASM distributed propagation changes as described in "RFC: Standalone ASM billing V2".

For the full picture of this feature, see: #9211 , #9444 and #9445

See also System Tests related changes: DataDog/system-tests#2522

Details:

The main change is that if ASM Standalone is enabled, propagation of distributed spans would reset (from upstream) unless they are part of a distributed span where there are AppSec events (signaled through the propagation tag _dd.p.appsec: 1).

It will also cut propagation downstream if there are no appsec events in the current or upstream spans.

Notice that AppSec events trigger a force keep, and that takes precedence over the received propagation in this PR.

Also notice that most tests start by creating a first span without an appsec event. This is due to the fact that ASM Standalone needs to maintain a minimum rate of 1 trace per minute regardless of upstream propagation or appsec events present, so that way we are not affected by that rate in the test.

Checklist

• Change(s) are motivated and described in the PR description
• Testing strategy is described if automated tests are not included in the PR
• Risks are described (performance impact, potential for breakage, maintainability)
• Change is maintainable (easy to change, telemetry, documentation)
• Library release note guidelines are followed or label changelog/no-changelog is set
• Documentation is included (in-code, generated user docs, public corp docs)
• Backport labels are set (if applicable)
• If this PR changes the public interface, I've notified @DataDog/apm-tees.

Reviewer Checklist

• Title is accurate
• All changes are related to the pull request's stated goal
• Description motivates each change
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Change is maintainable (easy to change, telemetry, documentation)
• Release note makes sense to a user of the library
• Author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: gnufede/APPSEC-53002-standalone-asm-propagation-2
Commit report: ce88f01
Test service: dd-trace-py

✅ 0 Failed, 118967 Passed, 55776 Skipped, 3h 33m 53.16s Total duration (5h 11m 8.11s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-06-10 14:23:24

Comparing candidate commit ce88f01 in PR branch gnufede/APPSEC-53002-standalone-asm-propagation-2 with baseline commit b0fdb1e in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 221 metrics, 9 unstable metrics.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 2.12766% with 184 lines in your changes missing coverage. Please review.

Project coverage is 10.27%. Comparing base (844117e) to head (ce88f01).
Report is 3 commits behind head on main.

Files	Patch %	Lines
tests/tracer/test_propagation.py	0.00%	176 Missing ⚠️
ddtrace/propagation/http.py	22.22%	7 Missing ⚠️
ddtrace/_trace/tracer.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #9482       +/-   ##
===========================================
- Coverage   75.88%   10.27%   -65.61%     
===========================================
  Files        1315     1285       -30     
  Lines      124706   123093     -1613     
===========================================
- Hits        94633    12650    -81983     
- Misses      30073   110443    +80370     

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